Tactile presentation device and control method

ABSTRACT

A tactile presentation device comprising: a contact face; a plurality of electrodes arranged along the contact face; a first control unit controlling operations of the electrodes for detecting contact or approach of an object toward the 5 contact face; a second control unit controlling operations of the electrodes for presenting a tactile sense to the contact face; and a third control unit causing a part of the plurality of the electrodes to be controlled by the first control unit, sequentially changing the electrode to be controlled by 10 the first control unit to another electrode among the plurality of the electrodes, and causing electrodes other than the electrode that is controlled by the first control unit to be controlled by the second control unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of application Ser. No. 17/661,968,filed on May 4, 2022, which is a divisional of U.S. patent applicationSer. No. 17/247,816 filed on Dec. 23, 2020, which is a divisional ofU.S. patent application Ser. No. 15/789,122 filed on Oct. 20, 2017,which claims priority under 35 U.S.C.§ 119(a) on Patent Application No.2016-207062 filed in Japan on Oct. 21, 2016 and Patent Application No.2017-155769 filed in Japan on Aug. 10, 2017, the entire contents ofwhich are hereby incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a tactile presentation device and acontrol method for controlling a tactile presentation device presentinga tactile sense on a contact face together with detecting contact on thecontact face.

Description of the Related Art

Technologies for presenting a tactile sense to a surface of a touchpanel using an electrostatic force have been developed. The presentationof a tactile sense represents causing a texture sense that can beperceived as a tactile sense when a user is brought into contact withthe surface of an object with which the user can be brought intocontact. For example, in a case where a tactile sense is presented to aspecific position on the surface of a touch panel, a user brought intocontact with the surface of the touch panel can notice the specificposition on the surface using a tactile sense. In PCT InternationalPublication No. 2014/002405 and U.S. Patent Application Publication No.2013/0307789, tactile presentation devices each presenting a tactilesense to the surface of a touch panel are disclosed.

A tactile presentation device including a touch panel needs to have botha function for detecting a contact position on the surface of the touchpanel and a function for presenting a tactile sense to the surface ofthe touch panel. In the tactile presentation device disclosed in PCTInternational Publication No. 2014/002405, a plurality of electrodes arearranged on in a planar shape, and voltages used for detecting a contactposition are supplied to the plurality of electrode in a certain period,and voltages used for presenting a tactile sense are supplied to theplurality of electrodes in the other period.

Accordingly, the tactile presentation device operates for detecting acontact position during the certain period and operates to present atactile sense during the other period. The function for detecting acontact position on the surface of the touch panel and the function forpresenting a tactile sense to the surface of the touch panel arerealized alternatingly in time.

SUMMARY OF THE INVENTION

In the tactile presentation device disclosed in PCT InternationalPublication No. 2014/002405, in the period in which the tactilepresentation device operates to detect a contact position on the surfaceof the touch panel, a tactile sense cannot be presented to the surfaceof the touch panel. For this reason, there is a problem in that atactile sense felt by a user during the use of the tactile presentationdevice is interrupted.

A tactile presentation device according to an aspect of the presentdisclosure, comprising: a contact face; a plurality of electrodesarranged along the contact face; a first control unit controllingoperations of the electrodes for detecting contact or approach of anobject toward the contact face; a second control unit controllingoperations of the electrodes for presenting a tactile sense to thecontact face; and a third control unit causing a part of the pluralityof the electrodes to be controlled by the first control unit,sequentially changing the electrode to be controlled by the firstcontrol unit to another electrode among the plurality of the electrodes,and causing electrodes other than the electrode that is controlled bythe first control unit to be controlled by the second control unit.

In a tactile presentation device according to the present disclosure, aplurality of electrodes are arranged along a contact face. Someelectrodes are used for detecting contact or approach of an objecttoward the contact face, and the other electrodes are used forpresenting a tactile sense to the contact face. The electrodes used fordetecting contact or approach of an object toward the contact face aresequentially changed. Each of the electrodes are used for detectingcontact or approach of an object at a specific timing and is used forpresenting a tactile sense at the other timings.

The above and further objects and features will more fully be apparentfrom the following detailed description with accompanying drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view that illustrates an example ofthe outer appearance of a tactile presentation device;

FIG. 2 is a block diagram that illustrates an example of the internalfunctional configurations of the tactile presentation device;

FIG. 3 is a block diagram that illustrates the internal configurationsof a tactile panel and a tactile panel driving unit according toEmbodiment 1;

FIG. 4 is a schematic circuit diagram that illustrates the internalconfiguration of an X electrode driving circuit according to Embodiment1;

FIG. 5 is a schematic circuit diagram that illustrates the internalconfiguration of a Y electrode driving circuit according to Embodiment1;

FIG. 6 is a schematic circuit diagram that illustrates the internalconfiguration of a touch panel driving circuit according to Embodiment1;

FIG. 7 is a timing diagram that illustrates an example of the operationof each electrode according to Embodiment 1;

FIG. 8 is a timing diagram that illustrates another example of theoperation of each electrode according to Embodiment 1;

FIG. 9 is a schematic plan view that illustrates a model of a tactilepanel for description;

FIGS. 10A to 10D are schematic views that illustrate a positionalrelation between an X electrode and a contact portion where a user'sfinger touches a contact face;

FIG. 11 is a schematic view that illustrates a relation between time andthe positions of a contact portion and an X electrode;

FIG. 12 is a characteristic diagram that illustrates a change in anelectrostatic force generated at a finger;

FIG. 13 is a schematic view that illustrates a relation between time andthe positions of a contact portion and an X electrode in a case wherethe position of the X electrode controlled for detecting contact isdiscretely changed in the model of the tactile panel illustrated in FIG.9 ;

FIG. 14 is a schematic circuit diagram that illustrates the internalconfiguration of a touch panel driving circuit according to Embodiment2;

FIG. 15 is a block diagram that illustrates the internal configurationsof a tactile panel and a tactile panel driving unit according toEmbodiment 3;

FIG. 16 is a schematic circuit diagram that illustrates the internalconfiguration of an electrode driving circuit according to Embodiment 3;

FIG. 17 is a schematic circuit diagram that illustrates the internalconfiguration of a touch panel driving circuit according to Embodiment3;

FIG. 18 is a timing diagram that illustrates an example of a change inthe state of each electrode with respect to time according to Embodiment3;

FIG. 19 is a schematic circuit diagram that illustrates the internalconfigurations of a touch panel driving circuit and a switching unitaccording to Embodiment 4;

FIG. 20 is a schematic view that illustrates an example of a tactilepanel according to Embodiment 4;

FIG. 21 is a timing diagram that illustrates an example of the operationof each electrode according to Embodiment 4;

FIGS. 22A to 22C are schematic views that illustrate the states of thetactile panel at specific timings according to Embodiment 4;

FIG. 23 is a block diagram that illustrates the internal configurationof a tactile panel according to Embodiment 5;

FIG. 24 is a block diagram that illustrates the internal configurationsof a tactile panel and a tactile panel driving unit according toEmbodiment 6;

FIG. 25 is a schematic circuit diagram that illustrates the internalconfiguration of a touch panel driving circuit according to Embodiment6;

FIG. 26 is a schematic circuit diagram that illustrates the internalconfiguration of an X electrode driving circuit according to Embodiment6;

FIGS. 27A to 27D are graphs that schematically illustrate the waveformsof voltages acquired by an X electrode driving circuit according toEmbodiment 6;

FIG. 28 is a schematic circuit diagram that illustrates the internalconfiguration of a Y electrode driving circuit according to Embodiment6;

FIGS. 29A to 29D are graphs that schematically illustrate the waveformsof voltages acquired by a Y electrode driving circuit according toEmbodiment 6;

FIG. 30 is a circuit diagram acquired by modeling a state in which an Xelectrode X₁ is connected to an AC voltage source through a currentdetecting unit, and a voltage generated by the AC voltage source issuperimposed in all the other electrodes;

FIG. 31 is a circuit diagram that models the states of the electrodesaccording to Embodiment 2; and

FIG. 32 is a circuit diagram that illustrates an example of theconfiguration of voltage superimposing units according to Embodiment 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be describedmore specifically with reference to the drawings.

Embodiment 1

FIG. 1 is a schematic perspective view that illustrates an example ofthe outer appearance of a tactile presentation device. The tactilepresentation device is a computer such as a smartphone or a tabletcomputer. The tactile presentation device includes a planar contact face11 for contact using a user's finger. On the contact face 11, an imageis displayed, and, when a user's finger is brought into contact with thecontact face 11, a tactile sense is presented, and a contact position onthe contact face 11 is detected.

FIG. 2 is a block diagram that illustrates an example of the internalfunctional configurations of a tactile presentation device. The tactilepresentation device includes: an arithmetic operation unit 31 thatperforms an arithmetic operation; a random access memory (RAM) 32 thatstores temporary data; a storage unit 33 that has non-volatility; and aninput/output unit 34 performing input/output of data.

The storage unit 33 is, for example, a hard disk or a nonvolatilesemiconductor memory. The input/output unit 34, for example, is acommunication unit that performs wired or wireless communication with anexternal device of the tactile presentation device. In addition, thetactile presentation device includes a display panel 36 such as a liquidcrystal display panel or an electroluminescence (EL) display panel thatdisplays an image. A display panel driving unit 35 driving the displaypanel 36 to display an image is connected to the display panel 36. Thedisplay panel driving unit 35 is connected to the arithmetic operationunit 31. The display panel driving unit 35 receives an input of imagedata from the arithmetic operation unit 31 and displays an image on thedisplay panel 36 based on the image data.

In addition, the tactile presentation device includes a tactile panel 1used for detecting a contact position on the contact face 11 togetherwith presenting a tactile sense. The tactile panel 1 overlaps with thedisplay panel 36. A tactile panel driving unit 2 that drives the tactilepanel 1 is connected to the tactile panel 1. The tactile panel drivingunit 2 is connected to the arithmetic operation unit 31.

FIG. 3 is a block diagram that illustrates the internal configurationsof a tactile panel 1 and a tactile panel driving unit 2 according toEmbodiment 1. The tactile panel 1 includes a transparent substrate 12such as a glass substrate. On the substrate 12, a plurality of linear Xelectrodes (first linear electrodes) 13 are arranged in parallel. InFIG. 3 , the X electrodes 13 are denoted using broken lines. Inaddition, on the substrate 12, a plurality of linear Y electrodes(second linear electrodes) 14 are arranged in parallel. The plurality ofX electrodes 13 and the plurality of Y electrodes 14 are insulated fromeach other. In addition, the plurality of X electrodes 13 and theplurality of Y electrodes 14 intersect each other. Here, a directionalong the linear X electrodes 13 will be set as an X direction, and adirection along the linear Y electrodes 14 will be set as a Y direction.A cover layer 15 having an insulating property is superimposed on thesubstrate 12 with the X electrodes 13 and the Y electrodes 14 interposedtherebetween. The surface of the cover layer 15 is the contact face 11.

The tactile panel driving unit 2 includes a touch panel driving circuit(first control unit) 22 for controlling the operations of the Xelectrodes 13 and the Y electrodes 14 used for detecting contact of anobject on the contact face 11. The touch panel driving circuit 22 is acircuit that is used for realizing the function of a touch paneldetecting contact of an object on the contact face 11 by using the Xelectrodes 13 and the Y electrodes 14. The tactile panel driving unit 2includes an X electrode driving circuit 23 used for controlling theoperations of the X electrodes 13 for presenting a tactile sense on thecontact face 11 and a Y electrode driving circuit 24 used forcontrolling the operations of the Y electrodes 14 for presenting atactile sense on the contact face 11. The X electrode driving circuit 23and the Y electrode driving circuit 24 are circuits used for presentinga tactile sense on the contact face 11 by using the X electrodes 13 andthe Y electrodes 14 and correspond to a second control unit. The tactilepanel driving unit 2 includes a first switching unit 25 that isconnected to the plurality of the X electrodes 13 and a second switchingunit 26 that is connected to the plurality of the Y electrodes 14. Thefirst switching unit 25 is configured to connect some X electrodes 13 tothe touch panel driving circuit 22 and connect the other X electrodes 13to the X electrode driving circuit 23 and to be able to switch theconnection of each X electrode 13 to one side to the other side. Thesecond switching unit 26 is configured to connect some Y electrodes 14to the touch panel driving circuit 22 and connect the other Y electrodes14 to the Y electrode driving circuit 24 and to be able to switch theconnection of each Y electrode 14 to one side to the other side.

Furthermore, the tactile panel driving unit 2 includes a control circuit21. The control circuit 21 is connected to the touch panel drivingcircuit 22, the X electrode driving circuit 23, the Y electrode drivingcircuit 24, the first switching unit 25, and the second switching unit26. In addition, the control circuit 21 is connected to the arithmeticoperation unit 31. The control circuit 21 receives an input of a controlsignal from the arithmetic operation unit 31 and controls the operationsof the touch panel driving circuit 22, the X electrode driving circuit23, the Y electrode driving circuit 24, the first switching unit 25, andthe second switching unit 26. The control circuit 21, the firstswitching unit 25, and the second switching unit 26 correspond to athird control unit.

FIG. 4 is a schematic circuit diagram that illustrates the internalconfiguration of the X electrode driving circuit 23 according toEmbodiment 1. The X electrode driving circuit 23 includes a plurality ofsingle-pole double-throw switches 231 and a first AC voltage source 232that generates an AC voltage having a predetermined first frequency f1.The internal circuit of the X electrode driving circuit 23 is configuredto connect each X electrode 13 connected through the first switchingunit 25 to one of the first AC voltage source 232 and the ground byusing each single-pole double-throw switch 231. Each single-poledouble-throw switch 231 is controlled by the control circuit 21 andperforms switching of a connection between each X electrode 13 and thefirst AC voltage source 232 or the ground. The internal circuit of the Xelectrode driving circuit 23 illustrated in FIG. 4 corresponds to afirst signal applying circuit.

FIG. 5 is a schematic circuit diagram that illustrates the internalconfiguration of the Y electrode driving circuit 24 according toEmbodiment 1. The Y electrode driving circuit 24 includes a plurality ofsingle-pole double-throw switches 241 and a second AC voltage source 242that generates an AC voltage having a predetermined second frequency f2.The internal circuit of the Y electrode driving circuit 24 is configuredto connect each Y electrode 14 connected through the second switchingunit 26 to one of the second AC voltage source 242 and the ground byusing each single-pole double-throw switch 241. Each single-poledouble-throw switch 241 is controlled by the control circuit 21 andperforms switching of a connection between each Y electrode 14 and thesecond AC voltage source 242 or the ground. The internal circuit of theY electrode driving circuit 24 illustrated in FIG. 5 corresponds to asecond signal applying circuit.

The tactile presentation device presents a tactile sense to the contactface 11 by using the operations of the X electrode driving circuit 23and the Y electrode driving circuit 24. In a case where a user bringshis finger into contact with the contact face 11, this finger isequivalent to an electrode that faces the X electrode 13 or the Yelectrode 14 with an insulating body interposed therebetween and isconnected to the ground through predetermined impedance. In a case wherea voltage is applied to the X electrode 13 or the Y electrode 14, anattracting force (electrostatic force) according to static electricityis generated between the X electrode 13 or the Y electrode 14 and thefinger. In a case where an AC voltage is applied, the electrostaticforce is periodically changed. As the electrostatic force is changed, africtional force between the contact face 11 and the finger isperiodically changed. When, the user traces the contact face 11 usinghis finger, a frictional force felt by the finger is periodicallychanged, and the user perceives a tactile sense. According to aconventional research, it has been disclosed that a tactile sense isperceived in a case where the frequency of an AC voltage is higher than5 Hz and lower than 500 Hz, and a tactile sense is not perceived in acase where the frequency is not within this range.

In a case where an AC voltage having the first frequency f1 is appliedto the X electrode 13, and an AC voltage having the second frequency f2is applied to the Y electrode 14, the electrostatic force is changed atthe first frequency f1 and the second frequency f2. In addition, a beatin which an electrostatic force is changed at the frequency of adifference between the first frequency f1 and the second frequency f2 isgenerated. According to a conventional research, it has been disclosedthat a tactile sense according to a beat is perceived in a case wherethe frequency of the beat is higher than Hz and lower than 1000 Hz, anda tactile sense according to a beat is not perceived in a case where thefrequency of the beat is not within this range.

In this embodiment, the first frequency f1 and the second frequency f2are set such that both the first frequency f1 and the second frequencyf2 are 500 Hz or higher, and the absolute value of a difference betweenthe first frequency f1 and the second frequency f2 is more than 10 Hzand less than 1000 Hz. For example, the first frequency f1=1000 Hz, andthe second frequency f2=1240 Hz. The X electrode driving circuit 23connects some X electrodes 13 among the X electrodes 13 connected to theX electrode driving circuit 23 to the first AC voltage source 232 andconnects the other X electrodes 13 to the ground under the control ofthe control circuit 21. The Y electrode driving circuit 24 connects someY electrodes 14 among the Y electrodes 14 connected to the Y electrodedriving circuit 24 to the second AC voltage source 242 and connects theother Y electrodes 14 to the ground under the control of the controlcircuit 21. For example, the tactile panel 1 includes five X electrodesX₀ to X₄ and six Y electrodes Y₀ to Y₅, the X electrode X₁ is connectedto the first AC voltage source 232, the Y electrode Y₁ is connected tothe second AC voltage source 242, and the X electrodes X₀ and X₂ to X₄and the Y electrodes Y₀ and Y₂ to Y₅ are connected to the ground. Inthis case, at a portion of the contact face 11 at which the X electrodeX₁ and the Y electrode Y₁ intersect with each other, a beat of 240 Hz isgenerated, and a user can perceive a tactile sense using his finger. Atportions at which the X electrode X₁ and the Y electrodes Y₀ and Y₂ toY₅ intersect with each other, while an electrostatic force is changed atthe frequency of 1000 Hz, a tactile sense is not perceived. At portionsat which the Y electrode Y₁ and the X electrodes X₀ and X₂ to X₄intersect with each other, while an electrostatic force is changed atthe frequency of 1240 Hz, a tactile sense is not perceived. At the otherportions, an electrostatic force is not changed, and a tactile sense isnot perceived. In this way, the tactile presentation device can presenta tactile sense at an arbitrary position on the contact face 11. Inaddition, a form in which the X electrode driving circuit 23 and the Yelectrode driving circuit 24 connect the X electrodes 13 and the Yelectrodes 14 not to the ground but to a predetermined DC power sourcemay be employed.

FIG. 6 is a schematic circuit diagram that illustrates the internalconfiguration of the touch panel driving circuit 22 according toEmbodiment 1. The touch panel driving circuit 22 includes a plurality ofsignal input units 221 and a plurality of current detecting units 222.Each of the signal input units 221 is connected to a signal lineconnected to the first switching unit 25. Each of the current detectingunits 222 is connected to a signal line connected to the secondswitching unit 26. The signal input units 221 are connected to the Xelectrodes 13 through the first switching unit 25, and the currentdetecting units 222 are connected to the Y electrodes 14 through thesecond switching unit 26. The signal input unit 221 inputs an AC signalto a corresponding X electrode 13. The current detecting unit 222detects a current signal flowing through a corresponding Y electrode 14.The internal circuit of the touch panel driving circuit 22 illustratedin FIG. 6 corresponds to a detection circuit.

At each portion at which the X electrode 13 and the Y electrode 14intersect with each other, electrostatic capacitance is generatedbetween the X electrode 13 and the Y electrode 14. In a case where thesignal input unit 221 inputs an AC signal to the X electrode 13, an ACcurrent flows between the X electrode 13 and the Y electrode 14 to whichthe current detecting unit 222 is connected, and the current detectingunit 222 detects the AC current. On the contact face 11, in a case wherea user's finger is brought into contact with a portion facing a portionat which the X electrode 13 and the Y electrode 14 intersect with eachother, electrostatic capacitance is generated between the X electrode 13or the Y electrode 14 and the finger, and the electrostatic capacitancebetween the X electrode 13 and the Y electrode 14 changes. In a casewhere the electrostatic capacitance between the X electrode 13 and the Yelectrode 14 changes, an AC current detected by the current detectingunit 222 changes. The operations of the first switching unit 25 and thesecond switching unit 26 are controlled by the control circuit 21, andthe X electrode 13 and the Y electrode 14 connected to the touch paneldriving circuit 22 are specified under the control of the controlcircuit 21. The control circuit 21 compares an AC current detected bythe current detecting unit 222 with a predetermined threshold, therebydetecting a change in the electrostatic capacitance between the Xelectrode 13 and the Y electrode 14 connected to the touch panel drivingcircuit 22. In addition, the control circuit 21 detects the positionwith which the user's finger is brought into contact by specifying the Xelectrode 13 and the Y electrode 14 connected to the touch panel drivingcircuit 22 in a case where the electrostatic capacitance changes. Thecontact position on the contact face 11 is a position facing a portionat which the X electrode 13 and the Y electrode 14 connected to thetouch panel driving circuit 22 intersecting with each other. The controlcircuit 21 outputs data representing the contact position to thearithmetic operation unit 31. In this way, the tactile presentationdevice detects a contact position on the contact face 11 by using amutual capacitance system.

In addition, the tactile presentation device may employ a form in whichnot only a contact position on the contact face 11 is detected, but alsoa position at which an object approaches is detected in a case where theconductive object such as a finger approaches the contact face 11 withina predetermined distance. In such a form, in a case where an objectapproaches the contact face 11 within a predetermined distance,electrostatic capacitance is generated between the X electrode 13 andthe object, and, similarly, a position approached by the object on thecontact face 11 is detected. In addition, the touch panel drivingcircuit 22 may employ a form in which the current detecting unit 222 isconnected to the X electrode 13, and the signal input unit 221 isconnected to the Y electrode 14.

Next, a process enabling both the detection of a contact position andthe presentation of a tactile sense that is performed by the tactilepresentation device will be described. The control circuit 21 performscontrol of the first switching unit 25 to connect each X electrode 13 toeither the touch panel driving circuit 22 or the X electrode drivingcircuit 23. Similarly, the control circuit 21 performs control of thesecond switching unit 26 to connect each Y electrode 14 to the touchpanel driving circuit 22 or the Y electrode driving circuit 24.

The control circuit 21 causes the first switching unit 25 to connectsome X electrodes 13 to the touch panel driving circuit 22 and connectsthe other X electrodes 13 to the X electrode driving circuit 23. Inaddition, the control circuit 21 causes the first switching unit tosequentially change the X electrodes 13 to be connected to the touchpanel driving circuit 22. When the X electrode 13 connected to the touchpanel driving circuit 22 is changed, the first switching unit 25connects the X electrode 13 that has been connected to the touch paneldriving circuit 22 until now to the X electrode driving circuit 23 andconnects some X electrodes 13 among a plurality of X electrodes 13 thathave been connected to the X electrode driving circuit 23 until now tothe touch panel driving circuit 22. For example, a state in which, amongthe X electrodes X₀ to X₄, the X electrode X₀ is connected to the touchpanel driving circuit 22, and the X electrodes X₁ to X₄ are connected tothe X electrode driving circuit 23 is changed to a state in which the Xelectrode X₁ is connected to the touch panel driving circuit 22, and theX electrodes X₀ and X₂ to X₄ are connected to the X electrode drivingcircuit 23. Then, similarly, the X electrode 13 connected to the touchpanel driving circuit 22 is sequentially changed.

Similarly, the control circuit 21 causes the second switching unit 26 toconnect some Y electrodes 14 to the touch panel driving circuit 22 andconnects the other Y electrodes 14 to the Y electrode driving circuit 24and sequentially changes the Y electrode 14 to be connected to the touchpanel driving circuit 22. When the Y electrode 14 connected to the touchpanel driving circuit 22 is changed, the second switching unit 26connects the Y electrode 14 that has been connected to the touch paneldriving circuit 22 until now to the Y electrode driving circuit 24 andconnects some Y electrodes 14 among a plurality of Y electrodes 14 thathave been connected to the Y electrode driving circuit 24 until now tothe touch panel driving circuit 22. For example, a state in which, amongthe Y electrodes Y₀ to Y₅, the Y electrode Y₀ is connected to the touchpanel driving circuit 22, and the Y electrodes Y₁ to Y₅ are connected tothe Y electrode driving circuit 24 is changed to a state in which the Yelectrode Y₁ is connected to the touch panel driving circuit 22, and theY electrodes Y₀ and Y₂ to Y₅ are connected to the Y electrode drivingcircuit 24. Then, similarly, the Y electrode 14 connected to the touchpanel driving circuit 22 is sequentially changed.

In addition, the control circuit 21, by controlling the single-poledouble-throw switches 231 of the X electrode driving circuit 23,connects the X electrode 13 corresponding to an area to which a tactilesense is to be presented to the first AC voltage source 232 and connectsthe other X electrodes 13 to the ground. Similarly, the control circuit21, by controlling the single-pole double-throw switches 241 of the Yelectrode driving circuit 24, connects the Y electrode 14 correspondingto an area to which a tactile sense is to be presented to the second ACvoltage source 242 and connects the other Y electrodes 14 to the ground.For example, it is assumed that an area surrounded by two-dot chainlines illustrated in FIG. 3 is a target area 16 to which a tactile senseis to be presented on the contact face 11, and the target area 16 is aportion facing intersections of the X electrodes X₁ and X₂ and the Yelectrodes Y₁ and Y₂. In such a case, the X electrode driving circuit 23connects the X electrodes X₁ and X₂ to the first AC voltage source 232and connects the other X electrodes 13 to the ground, and the Yelectrode driving circuit 24 connects the Y electrodes Y₁ and Y₂ to thesecond AC voltage source 242 and connects the other Y electrodes 14 tothe ground.

FIG. 7 is a timing diagram that illustrates an example of the operationof each electrode according to Embodiment 1. In FIG. 7 , the left sideto the right side represent the elapse of time, and t₀ to t₁₃ representrespective time points. FIG. 7 illustrates the states of the Xelectrodes X₀ to X₄ and the Y electrodes Y₀ to Y₅ at each time point. Astate in which the X electrode 13 or the Y electrode 14 is connected tothe ground is denoted by T_(G), a state in which the X electrode 13 isconnected to the first AC voltage source 232 is denoted by T_(A), and astate in which the Y electrode 14 is connected to the second AC voltagesource 242 is denoted by TB. In addition, a state in which the Xelectrode 13 is connected to the touch panel driving circuit 22 isdenoted by S_(T), and a state in which the Y electrode 14 is connectedto the touch panel driving circuit 22 is denoted by S_(R).

As illustrated in FIG. 7 , in a period of t₀ to t₆, the X electrode X₀is connected to the touch panel driving circuit 22. In addition, in aperiod of t₀ to t₁, the Y electrode Y₀ is connected to the touch paneldriving circuit 22, and, in a period of t₁ to t₂, the Y electrode Y₁ isconnected to the touch panel driving circuit 22, and the like. Thus,each of the Y electrodes Y₀ to Y₅ is sequentially connected to the touchpanel driving circuit 22. Accordingly, in the period of t₀ to t₆,detection of contact at positions on the contact face 11 correspondingto intersections between the X electrode X₀ and the Y electrodes Y₀ toY₅ is sequentially performed. Similarly, in a period of t₆ to t₁₂, the Xelectrode X₁ is connected to the touch panel driving circuit 22, each ofthe Y electrodes Y₀ to Y₅ is sequentially connected to the touch paneldriving circuit 22, and detection of contact at positions on the contactface 11 corresponding to intersections between the X electrode X₁ andthe Y electrodes Y₀ to Y₅ is sequentially performed. The process issimilarly repeated with the X electrode 13 connected to the touch paneldriving circuit 22 changed, and the detection of contact at positions onthe contact face 11 is sequentially performed. In this way, each of theX electrodes 13 and each of the Y electrodes 14 are sequentiallyconnected to the touch panel driving circuit 22, thereby beingsequentially controlled for detection of contact on the contact face 11.In other words, the contact face 11 is scanned for detection of acontact position. After the completion of the scanning of the wholecontact face 11, the control circuit 21 repeats the process ofsequentially connecting each X electrode 13 and each Y electrode 14 tothe touch panel driving circuit 22. In this way, the scanning isrepeated, and, in a case where a user contacts an arbitrary position onthe contact face 11, the contact point is detected. The scanning of thewhole contact face 11 is repeated 10 to 1000 times per one second. Forexample, the scanning of the whole contact face 11 is repeated 60 timesper one second.

As illustrated in FIG. 7 , in a period other than the period in whichthe electrode is connected to the touch panel driving circuit 22, the Xelectrodes X₁ and X₂ are connected to the first AC voltage source 232,and the Y electrodes Y₁ and Y₂ are connected to the second AC voltagesource 242, and the other X electrode 13 and the other Y electrodes 14are connected to the ground. As a result, a tactile sense is presentedto the target area 16 within the contact face 11. In this way, the Xelectrodes 13 and the Y electrodes 14 are controlled for presenting atactile sense to the contact face 11. As a result of the control of theX electrodes 13 and the Y electrodes 14 as described above, a part ofthe contact face 11 is used for detecting contact, and the other portionis used for presenting a tactile sense, and the position of the portionused for detecting contact is sequentially changed. Each portion on thecontact face 11 is used for detecting contact at a specific timing andis used for presenting a tactile sense at the other timings.

As above, in this embodiment, also in a period in which some Xelectrodes 13 and some Y electrodes 14 are controlled for detectingcontact on the contact face 11, the other X electrodes 13 and Yelectrodes 14 are controlled for presenting a tactile sense to thecontact face 11. For this reason, the tactile presentation device cansimultaneously perform the presentation of a tactile sense and thedetection of a contact position, and a tactile sense felt by a userduring the use of the tactile presentation device is not interrupted. Inaddition, the X electrode 13 and the Y electrode 14 controlled fordetecting contact on the contact face 11 are sequentially changed, andeach of the X electrode 13 and the Y electrode 14 is controlled forpresenting a tactile sense to the contact face 11 at timings other thanthe timing at which the electrodes are controlled for detecting contact.For this reason, contact can be detected at any position on the contactface 11, and a tactile sense can be presented to any position. While thepresentation of a tactile sense is not performed at a position at whichthe detection of contact on the contact face 11 is performed, theposition at which the contact is detected is sequentially moved, andaccordingly, the presentation of a tactile sense is not interrupted onthe whole contact face 11.

As illustrated in FIG. 7 , the control circuit 21 connects an Xelectrode 13 adjacent to the X electrode 13 connected to the touch paneldriving circuit 22 among the X electrodes 13 to the X electrode drivingcircuit 23 through the first switching unit 25. Similarly, the controlcircuit 21 connects a Y electrode 14 adjacent to the Y electrode 14connected to the touch panel driving circuit 22 among the Y electrodes14 to the Y electrode driving circuit 24 through the second switchingunit 26. In this way, the X electrode 13 that is adjacent to the Xelectrode 13 controlled for detecting contact on the contact face 11 andthe Y electrode 14 adjacent to the Y electrode 14 controlled fordetecting contact are controlled for presenting tactile senses. In acase where a plurality of electrodes controlled for detecting contact onthe contact face 11 are adjacent to each other, there is a problem inthat a portion not used for presenting a tactile sense becomes large. Inthis embodiment, electrodes adjacent to the electrodes controlled fordetecting contact on the contact face 11 are controlled for presenting atactile sense, and accordingly, the size of a portion not used forpresenting a tactile sense on the contact face 11 is minimized.

In this embodiment, a distance between the centers of the X electrodes13 adjacent to each other and a distance between the centers of the Yelectrodes 14 adjacent to each other are configured to be sufficientlysmaller than an area in which a person's finger is brought into contactwith the contact face 11. For this reason, the size of a portion notused for presenting a tactile sense to the contact face 11 issufficiently smaller than the size of a user's finger. In a portion inwhich a user's finger is brought into contact with the contact face 11,even in a case where a part does not present a tactile sense, a tactilesense is presented to the other part, and a tactile sense averaged overthe whole finger is perceived. Accordingly, a partly interruption of thepresentation of a tactile sense for detecting a contact position is notperceived by a user.

Conventionally, it is understood that the time resolution of a human'stactile sense is 10 ms. In this embodiment, a time interval for changingthe X electrode 13 controlled for detecting contact on the contact face11 is set to be shorter than 10 ms. In the example illustrated in FIG. 7, the length of the period of t₀ to t₆ and the length of the period oft₆ to t₁₂ is less than 10 ms. For example, the length of a period inwhich each X electrode 13 is continuously connected to the touch paneldriving circuit 22 is 1.6 ms. A time interval for changing the Yelectrode 14 controlled for detecting contact on the contact face 11 isshorter. In the example illustrated in FIG. 7 , the length of a periodin which each Y electrode 14 is continuously connected to the touchpanel driving circuit 22 is ⅙ of the length of the period in which eachX electrode 13 is continuously connected to the touch panel drivingcircuit 22. The length of a period in which a tactile sense is notpresented in a part of the contact face 11 is sufficiently shorter thanthe time resolution of the human tactile sense, and accordingly, a usercannot feel any loss of the tactile sense. Accordingly, a partlyinterruption of the presentation of a tactile sense for detecting acontact position cannot be perceived by a user.

FIG. 8 is a timing diagram that illustrates another example of theoperation of each electrode according to Embodiment 1. As illustrated inFIG. 8 , the tactile presentation device may have a form in which aplurality of Y electrodes 14 are simultaneously connected to the touchpanel driving circuit 22. In this case, the control circuit 21 causesthe second switching unit 26 to connect a plurality of Y electrodes 14not adjacent to each other to the touch panel driving circuit 22. Morespecifically, in a period of t₀ to t₁, Y electrodes Y₀ and Y₄ areconnected to the touch panel driving circuit 22, and, in a period of t₁to t₂, Y electrodes Y₁ and Y₅ are connected to the touch panel drivingcircuit 22. In other words, a plurality of Y electrodes 14 not adjacentto each other are controlled for simultaneously detecting contact on thecontact face 11.

By simultaneously controlling the plurality of Y electrodes 14 fordetecting contact on the contact face 11, a time required forsequentially controlling all the Y electrodes 14 for detecting contactcan be shortened. In accompaniment with this, a time required forcontrolling each X electrode 13 for detecting contact can be shortened.For this reason, a time required for detecting contact in all theportions of the contact face 11 can be shortened. In addition, thedetection of contact is performed simultaneously at a plurality ofpositions on the contact face 11. Accordingly, the tactile presentationdevice can quickly detect contact position in a case where a usercontacts an arbitrary position on the contact face 11. In addition,since the plurality of Y electrodes 14 controlled for detecting contactare not adjacent to each other, the size of a portion of the contactface 11 that is not used for presenting a tactile sense is minimized.Furthermore, the tactile presentation device may employ a form in whicha plurality of X electrodes 13 not adjacent to each other aresimultaneously controlled for detecting contact on the contact face 11.

Next, a distance between the centers of the electrodes adjacent to eachother and a time interval for changing the electrode controlled fordetecting contact on the contact face 11 will be further described. FIG.9 is a schematic plan view that illustrates a model of the tactile panel1 for description. A model in which a plurality of X electrodes 13 arearranged on the substrate 12, but no Y electrode 14 is arranged will beconsidered. The number of the X electrodes 13 is assumed to be 32, andthe distance between the centers of the X electrodes 13 adjacent to eachother is assumed to be 5 mm. The size of the contact face 11 in the Ydirection is 160 mm. A time for scanning all the X electrodes 13 is 16.6ms. A time required for controlling each X electrode 13 for detectingcontact is 0.519 ms. A contact portion where a user's finger touches thecontact face 11 is a square of which the length of one side is 10 mm.The moving speed of a finger with contacting on the contact face 11 is300 m m/s. An AC voltage applied to the X electrode 13 for presenting atactile sense is a voltage of 150 V with 100 Hz.

FIGS. 10A to 10D are schematic views that illustrate a positionalrelation between the X electrode 13 and a contact portion where a user'sfinger touches the contact face 11. In the figures, a plurality of Xelectrodes 13 are vertically aligned, and an X electrode 131 illustratedin the figures represents an X electrode 13 controlled for detectingcontact. X electrodes 13 other than the X electrode 131 are controlledfor presenting a tactile sense. A contact portion 41 where the fingertouches the contact face 11 is illustrated in the figures. In thefigures, the downward direction is a Y direction. States afterpredetermined times sequentially elapse from the state illustrated inFIG. 10A are respectively illustrated in FIGS. 10B, 10C, and 10D. In thefigures, arrows illustrate directions in which the finger moves. As theuser traces the contact face 11 in this direction by using a finger, africtional force is generated between the finger and the contact face11, and the user feels a tactile sense according to an electrostaticforce. As illustrated in the sequence of FIGS. 10A to 10D, the contactportion 41 where the finger touches the contact face 11 moves accordingto elapse of time. Similarly, according to scanning, the position of theX electrode 131 controlled for detecting contact among the X electrodes13 changes. The scanning speed of the X electrode 13 is much higher thanthe moving speed of the contact portion 41. As illustrated in FIG. 10C,in a case where the X electrode 131 and the contact portion 41 overlapeach other in the plan view, contact of the finger is detected, and anelectrostatic force operating on the finger for presenting a tactilesense is decreased.

FIG. 11 is a schematic view that illustrates a relation between time andthe positions of a contact portion 41 and an X electrode 131. In thedrawing, the vertical axis represents time, and the time elapses fromthe upper side toward the lower side. The horizontal axis represents aposition in the Y direction that is a distance from an end. In thedrawing, each hatched portion represents that an X electrode 13 locatedat a position corresponding to the portion at time corresponding to theportion is an X electrode 131 controlled for detecting contact. Theother portion represents that the X electrode 13 is controlled forpresenting a tactile sense. For example, an X electrode 13 positioned inthe first row, in other words, an X electrode 13 located at a positionof 0 to 5 mm in the Y direction is controlled for detecting contact in aperiod of 0 to 0.519 ms and is controlled for presenting a tactile sensein the other period. An X electrode 13 positioned in the second row, inother words, an X electrode 13 located at a position of 5 to 10 mm inthe Y direction is controlled for detecting contact in a period of 0.519to 1.038 ms and is controlled for presenting a tactile sense in theother period. In this way, the X electrode 131 controlled for detectingcontact is sequentially changed.

In FIG. 11 , the trajectory of the center of the contact portion 41 isillustrated using a solid line, and the trajectories of the upper endand the lower end of the contact portion 41 are illustrated using brokenlines. At time 0, the center of the contact portion 41 is located at aposition of 17.5 mm. This position coincides with the center of an Xelectrode 13 positioned in the fourth row in the Y direction. The userslides his finger on the contact face 11 at the speed of 300 mm/s in theY direction in a direction in which the numerical value of the positionof the Y direction increases. At time 5.19 ms, the position of thecenter of the contact portion 41 is 19.057 mm. As illustrated in FIG. 11, for example, at time 0.77 ms, the X electrodes 13 located at positionsfacing the range of the upper end to the lower end of the contactportion 41, in other words, the X electrodes 13 corresponding to all theareas of the contact portions 41 are controlled for presenting a tactilesense. At time 1.8 ms, X electrodes 13 corresponding to an area having ahalf area of the contact portion 41 are controlled for detectingcontact, and the other X electrodes 13 are controlled for presenting atactile sense. At this time, an electrostatic force generated at thefinger for presenting a tactile sense becomes a half of a normal case inaccordance with this area.

FIG. 12 is a characteristic diagram that illustrates a change in theelectrostatic force generated at a finger. The horizontal axisrepresents time, and the vertical axis represents a relative value ofthe electrostatic force. In a time period of 0 to 1.038 ms, the relativevalue of the electrostatic force is “1”. After time 1.038 ms, therelative value of the static electric force decreases up to 0.775 andslightly rises up to 0.794 over time 1.557 ms. After time 1.557 ms, therelative value of the static electric force decreases up to 0.5 and isuntil time 2.076 ms. After time 2.076 ms, the relative value of thestatic electric force rises to 0.6935 and decreases up to 0.678 overtime 2.595 ms. After time 2.595 ms, the relative value of the staticelectric force becomes 1. A period in which a decrease in theelectrostatic force occurs is merely 1.557 ms between time 1.038 ms andtime 2.595 ms. This period is sufficiently shorter than the timeresolution 10 ms of the tactile sense. The minimum value of the relativevalue of the electrostatic force is 0.5. As a result, an effect that aninterruption of the tactile sense is not perceived by the user can beacquired.

In addition, as the reason for user's no perception of an interruptionof the tactile sense, another reason may be considered. In the model ofthe tactile panel 1 illustrated in FIG. 9 , the frequency of the ACvoltage applied to the X electrode 13 for presenting a tactile sense is100 Hz, and the frequency of the electrostatic force is 200 Hz, which istwice the frequency of the AC voltage. This frequency mainly stimulatesa Pacinian corpuscle among human mechanoreceptors. The receptive fieldof the Pacinian corpuscle is wide, and an edge is unclearly detected ornot detected. For this reason, even in a case where an electrostaticforce is not generated in a half area of the contact portion 41, it isperceived by the user that a tactile sense is presented to the wholecontact portion 41. Even in a case where a difference between a casewhere an electrostatic force is generated in the whole contact portion41 and a case where an electrostatic force is generated only in a halfthereof can be perceived, the difference is perceived as a difference inthe strength of a stimulus, and a difference between presence/absence ofan edge is not perceived. Since an edge that becomes a clue for theperception of a change in the tactile sense cannot be detected, the usercannot perceive a change in the tactile sense, and no interruption ofthe tactile sense is considered to be perceived. In this way, the use ofthe electrostatic force of a frequency mainly stimulating a Paciniancorpuscle is considered to be one factor causing the effect of user's noperception of an interruption of the tactile sense.

Based on the viewpoints described above, in this embodiment, a distancebetween the centers of the X electrodes 13 adjacent to each other and adistance between the centers of the Y electrodes 14 adjacent to eachother are 5 mm or less. In the contact portion where the finger touchesthe contact face 11, a half or more in the X direction and a half ormore in the Y direction face X electrodes 13 and Y electrodes 14controlled for presenting a tactile sense. In addition, in thisembodiment, a value acquired by integrating a function of a temporalchange in the relative decreased amount of the electrostatic forcewithin the contact portion 41 as illustrated in FIG. 12 with respect totime is configured to be less than 10 ms. Here, the concept of a valueacquired by integrating the function of a temporal change in therelative decreased amount of the electrostatic force with respect totime will be supplemented. In FIG. 12 , the vertical axis represents theelectrostatic force, in other words, a force, and the horizontal axisrepresents the time. Accordingly, a value acquired by integrating thefunction of a temporal change in the relative decreased amount of theelectrostatic force with respect to time can be regarded as an analogyof an impulse called in dynamics. The magnitude of an interruption ofthe tactile sense perceived according to a decrease in the electrostaticforce is a function of the magnitude of a decrease in the electrostaticforce and a time in which the electrostatic force is decreased. Themagnitude of the interruption of the tactile sense perceived in apredetermined range is a monotonous increasing function of an impulsethat is the product of the magnitude of the decrease in theelectrostatic force and the time in which the electrostatic force isdecreased. By configuring the value acquired by integrating the functionof the temporal change in the relative decreased amount of theelectrostatic force with respect to time to be smaller than the timeresolution, which is 10 ms, of the human tactile sense, the user'sperception of an interruption in the presentation of a tactile sensedisappears. In the example illustrated in FIG. 12 , a decrease in theelectrostatic force occurs within a shorter period than 10 ms, which isthe time resolution of a tactile sense, and a perceived electrostaticforce is averaged over the whole finger to be non-zero even in the casewhere the electrostatic force is decreased, and accordingly, aninterruption of the presentation of a tactile sense is not perceived bya user. In addition, even in a case where an average value of theelectrostatic force over the whole finger is zero, by configuring thetime in which the electrostatic force is zero to be shorter than 10 ms,an interruption of the presentation of a tactile sense is not perceivedby the user.

In the description of this embodiment presented above, while a form inwhich an electrode adjacent to an electrode controlled for detectingcontact on the contact face 11 is an electrode controlled next fordetection of contact has been explained, the tactile presentation devicemay employ a form in which an electrode not adjacent to an electrodecontrolled for detection of contact is an electrode controlled next forthe detection of contact. FIG. 13 is a schematic view that illustrates arelation between time and the positions of a contact portion 41 and an Xelectrode 131 in a case where the position of the X electrode 131controlled for detecting contact is discretely changed in the model ofthe tactile panel 1 illustrated in FIG. 9 . In the drawing, the verticalaxis represents time, and the time elapses from the upper side towardthe lower side. In the drawing, T_(s) is T_(s)=0.519 ms. The horizontalaxis represents a position in the Y direction that is a distance from anend. In the drawing, each hatched portion represents that an X electrode13 located at a position corresponding to the portion at timecorresponding to the portion is an X electrode 131 controlled fordetecting contact. The other portion represents that the X electrode 13is controlled for presenting a tactile sense.

In the example illustrated in FIG. 13 , in a time period of 0 to T_(s),an X electrode 13 located at a position of 0 to 5 mm in the Y direction,in other words, an X electrode 13 positioned in the first row iscontrolled for detection of contact. In a time period of T_(s) to 2T_(s), an X electrode 13 located at a position of 75 to 80 mm in the Ydirection, in other words, an X electrode 13 positioned in the 16th rowis controlled for detection of contact. Subsequently, in a time periodof 2 T_(s) to 3 T_(s), an X electrode 13 located at a position of 10 to15 mm in the Y direction, in other words, an X electrode 13 positionedin the 3rd row is controlled for detection of contact. In this way, theposition of the X electrode 131 controlled for detection of contact ischanged to the 16th row after the first row, and thereafter, isdiscretely changed to the 3rd row, the 18th row, the 5th row, the 20throw, the 7th row, and the like.

By discretely changing the position of the X electrode 131, timings atwhich the electrostatic force decreases in a plurality of areas includedwithin the contact portion 41 are discrete. For this reason, the periodin which the presentation of the tactile sense is interrupted within thecontact portion 41 is further shortened. Accordingly, the effect ofuser's no perception of an interruption of the tactile sense is furtherimproved.

In FIG. 13 , two examples of the trajectories of the contact portion 41are illustrated. The trajectory of the center of the contact portion 41is illustrated using a solid line, and the trajectories of the upper endand the lower end of the contact portion 41 are illustrated using brokenlines. The trajectories illustrated in a left portion of FIG. 13 aretrajectories of a contact portion 41 that is located at the position of17.5 mm at time 0 and moves at the speed of 300 mm/s in a direction inwhich the numerical value of the position of the Y direction increases.According to these trajectories, the electrostatic force within thecontact portion 41 is 78% of a normal case in a time period of 2 T_(s)to 3 T_(s) and is 70% in a time period of 4 T_(s) to 5 T_(s). On theother hand, in a period interposed between both the periods, there is nodecrease in the electrostatic force. The length of the period in which adecrease in the electrostatic force occurs is a maximum of T_(s) and isextremely short. The length of this period is shorter than 1.557 msillustrated in FIG. 12 and is sufficiently shorter than 10 ms that isthe time resolution of the tactile sense. For this reason, aninterruption of the tactile sense is not perceived by the user. Thetrajectories illustrated in a right portion of FIG. 13 are trajectoriesof a contact portion 41 that is located at the position of 120 mm attime 0 and moves at the speed of 600 mm/s in a direction in which thenumerical value of the position of the Y direction decreases. Also inthe case of tracing these trajectories, the period in which a decreasein the electrostatic force occurs is a maximum of T_(s), which isextremely short, and an interruption of the tactile sense is notperceived by the user.

As in the example illustrated in FIG. 13 , the tactile presentationdevice may employ a form in which the positions of the X electrode 13and the Y electrode 14 controlled for detecting contact on the contactface 11 may be discretely changed among the X electrodes 13 and the Yelectrodes 14. By discretely changing the positions of the X electrode13 and the Y electrode 14 to be controlled for detecting contact,timings at which the electrostatic force decreases in a plurality ofareas included within the contact portion 41 where the user's fingertouches the contact face 11 are discrete. For this reason, similar tothe example illustrated in FIG. 13 , the period in which theelectrostatic force decreases within the contact portion is furthershortened, and accordingly, the effect of user's no perception of aninterruption of the tactile sense is further improved.

Embodiment 2

A tactile presentation device according to Embodiment 2 detects acontact position on a contact face 11 by using a method difference fromthat of Embodiment 1. The configuration of the tactile presentationdevice is similar to that of the case of Embodiment 1 illustrated inFIGS. 1 to 3 except for the inside of a touch panel driving circuit 22.

FIG. 14 is a schematic circuit diagram that illustrates the internalconfiguration of the touch panel driving circuit 22 according toEmbodiment 2. The touch panel driving circuit 22 includes a plurality ofcurrent detecting units 223 and a plurality of AC voltage sources 224.Each current detecting unit 223 is connected to a signal line connectedto a first switching unit 25 and is connected to a signal line connectedto a second switching unit 26. The AC voltage source 224 is connected toeach current detecting unit 223. The AC voltage sources 224 areconnected to the ground. Through the first switching unit 25, thecurrent detecting units 223 are connected to X electrodes 13, the ACvoltage sources 224 apply voltages to the X electrodes 13, and thecurrent detecting units 223 detect currents flowing through the Xelectrodes 13. Similarly, through the second switching unit 26, thecurrent detecting units 223 are connected to Y electrodes 14, the ACvoltage sources 224 apply voltages to the Y electrodes 14, and thecurrent detecting units 223 detect currents flowing through the Yelectrodes 14. The internal circuit of the touch panel driving circuit22 illustrated in FIG. 14 corresponds to a detection circuit.

In a state in which a user's finger is not brought into contact with thecontact face 11, even when voltages are applied from the AC voltagesource 224 to the X electrodes 13 or the Y electrodes 14, currentshardly flow, and currents detected by the current detecting units 223are almost zero. More specifically, a slight current flows through theparasitic capacitance of each X electrode 13 and the parasiticcapacitance of each Y electrode 14. The current flowing through theparasitic capacitance is called a parasitic current. Each currentdetecting unit 223 detects a parasitic current. In a case where a user'sfinger is brought into contact with a portion on the contact face 11that faces an X electrode 13 connected to the touch panel drivingcircuit 22, electrostatic capacitance is generated between the Xelectrode 13 and the finger. An AC voltage is applied from the ACvoltage source 224, a current according to the electrostatic capacitanceflows through the X electrode 13, and the current detecting unit 223detects the current. Similarly, electrostatic capacitance is generatedbetween a user's finger brought into contact with the contact face 11and the Y electrode 14 connected to the touch panel driving circuit 22,a current according to the electrostatic capacitance flows through the Yelectrode 14, and the current detecting unit 223 detects the current.The norm of the current detected by the current detecting unit 223 isproportional to the generated electrostatic capacitance. In moredetails, an increased amount of the norm of the current detected by thecurrent detecting unit 223 from a norm of a parasitic current isproportional to the generated electrostatic capacitance.

The operations of the first switching unit 25 and the second switchingunit 26 are controlled by a control circuit 21, and the X electrode 13and the Y electrode 14 connected to the touch panel driving circuit 22are specified under the control of the control circuit 21. The controlcircuit 21 detects generation of electrostatic capacitance in accordancewith the norm of the current detected by the current detecting unit 223being a predetermined value or more for each of the X electrodes 13 andthe Y electrodes 14 connected to the touch panel driving circuit 22. Inaddition, the control circuit 21 specifies the X electrode 13 and the Yelectrode 14 in which the electrostatic capacitance is generated, inother words, the X electrode 13 and the Y electrode 14 connected to thetouch panel driving circuit 22 when the electrostatic capacitance isgenerated, thereby detecting a position with which the user's finger isbrought into contact. The contact position is a position on the contactface 11 that faces a portion at which the X electrode 13 and the Yelectrode 14, in which the electrostatic capacitance is generated,intersect each other. The control circuit 21 outputs data representingthe contact position to an arithmetic operation unit 31. In this way,the tactile presentation device detects a contact position on thecontact face 11 by using a self capacitance system.

In addition, the tactile presentation device may employ a form in whichnot only a contact position on the contact face 11 is detected but alsoa position at which an object approaches is detected in a case where theconductive object such as a finger approaches the contact face 11 withina predetermined distance. In such a form, in a case where an objectapproaches the contact face 11 within a predetermined distance,electrostatic capacitance is generated between the X electrode 13 andthe Y electrode 14 and the object, and, similarly, a position approachedby the object on the contact face 11 is detected.

The control circuit 21, similar to Embodiment 1, by controlling thefirst switching unit 25 and the second switching unit 26, connects someX electrodes 13 and some Y electrodes 14 to the touch panel drivingcircuit 22 and sequentially changes the X electrodes 13 and the Yelectrodes 14 connected to the touch panel driving circuit 22. Inaddition, similar to Embodiment 1, the control circuit 21 connects the Xelectrodes 13 not connected to the touch panel driving circuit 22 to theX electrode driving circuit 23 and connects the Y electrodes 14 notconnected to the touch panel driving circuit 22 to the Y electrodedriving circuit 24. In other words, also in this embodiment, some Xelectrodes 13 and some Y electrodes 14 are controlled for detectingcontact on the contact face 11, and the X electrodes 13 and the Yelectrodes 14 controlled for detecting contact are sequentially changed,and each of the X electrodes 13 and the Y electrodes 14 is controlledfor presenting a tactile sense to the contact face 11 at timings otherthan the timing at which the electrodes are controlled for detectingcontact. For this reason, also in this embodiment, the tactilepresentation device can simultaneously perform the presentation of atactile sense and the detection of a contact position, and a tactilesense felt by a user during the use of the tactile presentation deviceis not interrupted.

In Embodiments 1 and 2 described above, while a form in which thecontrol circuit 21 is included in addition to the touch panel drivingcircuit 22, the X electrode driving circuit 23, the Y electrode drivingcircuit 24, the first switching unit 25, and the second switching unit26 is illustrated, the tactile presentation device may employ a form notincluding the control circuit 21. For example, the tactile presentationdevice may employ a form in which the touch panel driving circuit 22 hasfunctions equivalent to those of the control circuit 21. In addition,the tactile presentation device may employ a form in which the functionsequivalent to those of the control circuit 21 are included in the touchpanel driving circuit 22, the X electrode driving circuit 23, the Yelectrode driving circuit 24, the first switching unit 25, and thesecond switching unit 26 in a distributed manner. Furthermore, thetactile presentation device may employ a form in which the operations ofthe touch panel driving circuit 22, the X electrode driving circuit 23,the Y electrode driving circuit 24, the first switching unit 25, and thesecond switching unit 26 are directly controlled by the arithmeticoperation unit 31.

In Embodiments 1 and 2, while a form in which a tactile sense ispresented using a beat between AC voltages applied to a specific Xelectrode 13 and a specific Y electrode 14 is illustrated, the tactilepresentation device may employ a form in which a tactile sense ispresented using a method other than methods that are generally known.For example, the tactile presentation device may employ a form in whicha tactile sense is presented by applying the same AC voltage to aspecific X electrode 13 and a specific Y electrode 14 or a form in whicha tactile sense is presented by applying the same AC voltage to all theX electrodes 13 and all the Y electrodes 14. In addition, the tactilepresentation device may employ a form in which a tactile sense ispresented by applying voltages having opposite polarities to the Xelectrodes 13 adjacent to each other or the Y electrodes 14 adjacent toeach other.

Furthermore, the tactile presentation device may employ a form in whicha position at which an object approaches or is in contact with thecontact face 11 is detected using a generally-known method other thanthe methods described in Embodiments 1 and 2 described above. Forexample, the tactile presentation device may employ a form in which acurrent value of a voltage signal applied to the X electrode 13 and theY electrode 14 for presenting a tactile sense is measured, and contactor approach of an object is detected according to a change in themeasured current value.

In Embodiments 1 and 2, while a form in which the X electrodes 13 andthe Y electrodes 14 are arranged such that the intersections of the Xelectrodes 13 and the Y electrodes 14 are arranged in a matrix patternhas been illustrated, the tactile presentation device may employ a formin which the X electrodes 13 and the Y electrodes 14 are arranged in anyother form. For example, the tactile presentation device may employ aform in which the X electrodes 13 and the Y electrodes 14 are arrangedsuch that the intersections of the X electrodes 13 and the Y electrodes14 are arranged in a shape to be represented through a tactile sense.

Embodiment 3

In Embodiment 3, a form is illustrated in which electrodes are arrangedin a form different from those of Embodiments 1 and 2. The configurationof a tactile presentation device is similar to that of the case ofEmbodiment 1 illustrated in FIGS. 1 and 2 except for the insides of atactile panel 1 and a tactile panel driving unit 2.

FIG. 15 is a block diagram that illustrates the internal configurationsof the tactile panel 1 and the tactile panel driving unit 2 according toEmbodiment 3. The tactile panel 1 includes a transparent substrate 12such as a glass substrate, and a plurality of electrodes 17 are arrangedon the substrate 12. The shape of each electrode 17 is a rectangle, andthe electrodes 17 are arranged in a matrix pattern. FIG. 15 illustratesan example in which the electrodes 17 are arranged in 6 rows x 9columns. A wiring 18 is connected to each electrode 17. In FIG. 15 ,while a reference numeral 17 is assigned to one electrode and areference numeral 18 is assigned to one wiring, all the rectangularelectrodes illustrated in FIG. 15 are electrodes 17, and all the wiringsconnected to the electrodes 17 are wirings 18. A direction along one rowillustrated in FIG. 15 is set as an X direction, and a direction alongone column is set as a Y direction. The plurality of electrodes 17 areinsulated from each other. On the substrate 12, a cover layer 15 havingan insulating property is superimposed with the electrodes 17 interposedtherebetween. The surface of the cover layer 15 is the contact face 11.

The tactile panel driving unit 2 includes a touch panel driving circuit(first control unit) 22 used for controlling the operations of theelectrodes 17 for detecting contact on the contact face 11. The tactilepanel driving unit 2 includes an electrode driving circuit 27 used forcontrolling the operations of the electrodes 17 for presenting a tactilesense to the contact face 11. The electrode driving circuit 27corresponds to a second control unit. In addition, the tactile paneldriving unit 2 includes a switching unit 28 to which a plurality ofwirings 18 are connected. The electrodes 17 are connected to theswitching unit 28 through the wirings 18. The switching unit 28 connectssome electrodes 17 to the touch panel driving circuit 22, connects theother electrodes 17 to the electrode driving circuit 27, and isconfigured to switch the connection of each electrode 17 to one side tothe other side.

The tactile panel driving unit 2 includes a control circuit 21. Thecontrol circuit 21 is connected to the touch panel driving circuit 22,the electrode driving circuit 27, and the switching unit 28. Inaddition, the control circuit 21 is connected to an arithmetic operationunit 31. The control circuit 21 receives an input of a control signalfrom the arithmetic operation unit 31 and controls the operations of thetouch panel driving circuit 22, the electrode driving circuit 27, andthe switching unit 28. The control circuit 21 and the switching unit 28correspond to a third control unit.

FIG. 16 is a schematic circuit diagram that illustrates the internalconfiguration of the electrode driving circuit 27 according toEmbodiment 3. The electrode driving circuit 27 includes a plurality ofsingle-pole double-throw switches 271 and an AC voltage source 272 thatgenerates an AC voltage having a predetermined frequency. The internalcircuit of the electrode driving circuit 27 is configured to connecteach wiring 18 connected through the switching unit 28 to one of the ACvoltage source 272 and the ground by using each single-pole double-throwswitch 271. Each single-pole double-throw switch 271 is controlled bythe control circuit 21 and performs switching of a connection betweeneach wiring 18 and the AC voltage source 272 or the ground. In otherwords, the electrode driving circuit 27 connects the electrode 17connected through the switching unit 28 and the wiring 18 to one of theAC voltage source 272 and the ground, and switches the connection underthe control of the control circuit 21. The internal circuit of theelectrode driving circuit 27 illustrated in FIG. 16 corresponds to asignal applying circuit.

The tactile presentation device presents a tactile sense to the contactface 11 by using the operation of the electrode driving circuit 27. In acase where an AC voltage is applied to an electrode 17 facing a user'sfinger brought into contact with the contact face 11, an electrostaticforce that periodically changes is generated between the electrode 17and the finger. When the user traces the contact face 11 by using afinger, a frictional force felt by the finger periodically changes,whereby a tactile sense is presented. The frequency of the AC voltageapplied by the AC voltage source 272 is higher than 5 Hz and lower than1000 Hz. For example, the frequency is 120 Hz. For this reason, a usercan perceive a tactile sense on the contact face 11.

The electrode driving circuit 27, under the control of the controlcircuit 21, connects some electrodes 17 among electrodes 17 connected tothe electrode driving circuit 27 to the AC voltage source 272 andconnects the other electrodes 17 to the ground. In a portion on thecontact face 11 that faces the electrode 17 connected to the AC voltagesource 272, a periodical electrostatic force is generated, and a usercan perceive a tactile sense by using his finger. In the other portions,an electrostatic force is not generated, and a tactile sense is notperceived. In this way, the tactile presentation device can present atactile sense at an arbitrary position of the contact face 11. Theelectrode driving circuit 27 may employ a form in which the electrodes17 are connected not to the ground but a predetermined DC power source.

FIG. 17 is a schematic circuit diagram that illustrates the internalconfiguration of the touch panel driving circuit 22 according toEmbodiment 3. The touch panel driving circuit 22 includes a plurality ofcurrent detecting units 223 and a plurality of AC voltage sources 224.Each current detecting unit 223 is connected to a signal line connectedto the switching unit 28. The AC voltage source 224 is connected to eachcurrent detecting unit 223. The AC voltage source 224 is connected tothe ground. Through the switching unit 28 and a wiring 18, the currentdetecting unit 223 is connected to the electrode 17, the AC voltagesource 224 applies a voltage to the electrode 17, and the currentdetecting unit 223 detects a current flowing through the electrode 17.The internal circuit of the touch panel driving circuit 22 illustratedin FIG. 17 corresponds to a detection circuit.

In a state in which a user's finger is not brought into contact with thecontact face 11, even when a voltage is applied from the AC voltagesource 224 to the electrode 17, a current hardly flows, and a currentdetected by the current detecting unit 223 is almost zero. In moredetails, similar to Embodiment 2, the current detecting unit 223 detectsa parasitic current. In a case where a user's finger is brought intocontact with a portion on the contact face 11 that faces the electrode17 connected to the touch panel driving circuit 22, electrostaticcapacitance is generated between the electrode 17 and the finger. An ACvoltage is applied from the AC voltage source 224, a current increasedaccording to the electrostatic capacitance flows through the electrode17, and the current detecting unit 223 detects the current. An increasedamount of the norm of the current detected by the current detecting unit223 is proportional to the generated electrostatic capacitance.

The operation of the switching unit 28 is controlled by the controlcircuit 21, and the electrode 17 to be connected to the touch paneldriving circuit 22 is specified under the control of the control circuit21. The control circuit 21 detects generation of electrostaticcapacitance in accordance with the norm of the current detected by thecurrent detecting unit 223 being a predetermined value or more for eachelectrode 17 connected to the touch panel driving circuit 22. Inaddition, the control circuit 21 specifies an electrode 17 in which theelectrostatic capacitance is generated, in other words, an electrode 17connected to the touch panel driving circuit 22 when the electrostaticcapacitance is generated, thereby detecting a position with which theuser's finger is brought into contact. The contact position is aposition on the contact face 11 that faces the electrode 17 in which theelectrostatic capacitance is generated. The control circuit 21 outputsdata representing the contact position to the arithmetic operation unit31. In this way, the tactile presentation device detects a contactposition on the contact face 11 by using a self-capacitance system.

In addition, the tactile presentation device may employ a form in whichnot only a contact position on the contact face 11 is detected but alsoa position at which an object approaches is detected in a case where theconductive object such as a finger approaches the contact face 11 withina predetermined distance. In such a form, in a case where an objectapproaches the contact face 11 within a predetermined distance,electrostatic capacitance is generated between the electrode 17 and theobject, and, similarly, a position approached by the object on thecontact face 11 is detected.

The control circuit 21 performs control of the switching unit 28 toconnect each electrode 17 to either the touch panel driving circuit 22or the electrode driving circuit 27. The control circuit 21 causes theswitching unit 28 to connect some electrodes 17 to the touch paneldriving circuit 22 and connects the other electrodes 17 to the electrodedriving circuit 27. In addition, the control circuit 21 causes theswitching unit 28 to sequentially change the electrodes 17 to beconnected to the touch panel driving circuit 22. When the electrode 17connected to the touch panel driving circuit 22 is changed, theswitching unit 28 connects the electrode 17 that has been connected tothe touch panel driving circuit 22 until now to the electrode drivingcircuit 27 and connects some electrodes among a plurality of electrodes17 that have been connected to the electrode driving circuit 27 untilnow to the touch panel driving circuit 22. In addition, the controlcircuit 21, by controlling the single-pole double-throw switch 271 ofthe electrode driving circuit 27, connects an electrode 17 correspondingto an area to which a tactile sense is to be presented among theelectrodes 17 connected to the electrode driving circuit 27 to the ACvoltage source 272 and connects the other electrodes 17 to the ground.

Under the control of the control circuit 21, each of the plurality ofelectrodes 17 is sequentially connected to the touch panel drivingcircuit 22, and detection of contact at a position on the contact face11 that faces each electrode 17 is sequentially performed. Bysequentially connecting each electrode 17 to the touch panel drivingcircuit 22, each electrode 17 is sequentially controlled for detectingcontact on the contact face 11. In other words, the contact face 11 isscanned for detection of a contact position. After the completion of thescanning of the whole contact face 11, the control circuit 21 repeatsthe process of sequentially connecting each electrode 17 to the touchpanel driving circuit 22. In this way, the scanning is repeated, and, ina case where a user contacts an arbitrary position on the contact face11, the contact point is detected. The scanning of the whole contactface 11 is repeated 10 to 1000 times per one second. For example, thescanning of the whole contact face 11 is repeated 120 times per onesecond. In a period other than the period in which the electrode 17 isconnected to the touch panel driving circuit 22, the electrode 17 isconnected to the electrode driving circuit 27 under the control of thecontrol circuit 21. Some electrodes 17 are connected to the AC voltagesource 272, and the other electrodes 17 are connected to the ground. Asa result, a tactile sense is presented to the contact face 11. In thisway, the electrodes 17 are controlled for presenting a tactile sense tothe contact face 11.

FIG. 18 is a timing diagram that illustrates an example of a change ineach electrode 17 state with respect to time according to Embodiment 3.The vertical axis represents the position of each electrode 17. Numbersof 0 to 8 are assigned to the electrodes 17 disposed along the Xdirection, numbers of 0 to 5 are assigned to the electrodes 17 disposedalong the Y direction, and the position of each electrode 17 isrepresented using a combination of an X-direction number and aY-direction number. The horizontal axis represents the elapse of time,and, the elapse of time is represented by attached numbers of 1 to 9 toperiods dividing the time. The length of each period is 0.925 ms. In thedrawing, each hatched portion represents that an electrode 17 located ata position corresponding to the portion in a period corresponding to theportion is controlled for detecting contact. The other portionsrepresent that the electrodes 17 are controlled for presenting a tactilesense. A column of a period to which number “1” is assigned representsthat state of each electrode 17 in a time period of 0 to 0.925 ms, and acolumn of a period to which number “2” is assigned represents that stateof each electrode 17 in the next 0.925 ms. In the period to which number“1” is assigned, the electrodes 17 controlled for detecting contact aresix electrodes 17 of which positions represented by (X, Y) are (0, 0),(0, 3), (3, 0), (3, 3), (6, 0), and (6, 3). The other electrodes 17 arecontrolled for presenting a tactile sense. In the period to which number“2” is assigned, the electrodes 17 controlled for detecting contact aresix electrodes 17 of (0, 1), (0, 4), (3, 1), (3, 4), (6, 1), and (6, 4).As illustrated in FIG. 18 , in periods to which numbers “1” to “9” areassigned, all the electrodes 17 are sequentially controlled forpresenting a tactile sense, and the scanning of the whole contact face11 is completed in a time of 8.3 ms.

As above, in this embodiment, also in a period in which some electrodes17 are controlled for detecting contact on the contact face 11, theother electrodes 17 are controlled for presenting a tactile sense to thecontact face 11. For this reason, the tactile presentation device cansimultaneously perform the presentation of a tactile sense and thedetection of a contact position. In addition, the electrode 17controlled for detecting contact on the contact face 11 is sequentiallychanged, and each electrode 17 is controlled for presenting a tactilesense to the contact face 11 at timings other than the timing at whichthe electrode 17 is controlled for detecting contact. While thepresentation of a tactile sense is not performed at a position at whichthe detection of contact on the contact face 11 is performed, theposition at which the contact is detected is sequentially moved, andaccordingly, the presentation of a tactile sense is not interrupted onthe whole contact face 11. Also in this embodiment, the tactilepresentation device can simultaneously perform the presentation of atactile sense and the detection of a contact position, and a tactilesense felt by a user during the use of the tactile presentation deviceis not interrupted.

In addition, in this embodiment, the control circuit 21 causes theswitching unit 28 to connect an electrode 17 adjacent to an electrode 17connected to the touch panel driving circuit 22 to the electrode drivingcircuit 27. In this way, the electrode 17 adjacent to the electrode 17controlled for detecting contact on the contact face 11 is controlledfor presenting a tactile sense. For this reason, the size of a portionnot used for presenting a tactile sense on the contact face 11 isminimized.

In the example illustrated in FIG. 18 , a plurality of electrodes 17 notadjacent to each other are simultaneously controlled for detectingcontact on the contact face 11. Accordingly, a time required forsequentially controlling all the electrodes 17 for detecting contact canbe shortened, and a time required for scanning the whole contact face 11can be shortened. In addition, since contact is detected simultaneouslyin a plurality of positions on the contact face 11, the tactilepresentation device can quickly detect contact positions.

In this embodiment, a distance between the centers of the electrodes 17adjacent to each other is configured to be sufficiently smaller than anarea in which a person's finger is brought into contact with the contactface 11. For example, in both the X direction and the Y direction, adistance between the centers of the electrodes 17 adjacent to each otheris configured to be 5 mm. The size of a portion not used for presentinga tactile sense to the contact face 11 is sufficiently smaller than thesize of a user's finger. In a portion in which a user's finger isbrought into contact with the contact face 11, even in a case where apart does not present a tactile sense, a tactile sense is presented tothe other part, and a tactile sense averaged over the whole finger isperceived.

In this embodiment, a time interval for changing the electrode 17controlled for detecting contact on the contact face 11 is set to beshorter than 10 ms that is the time resolution of the tactile sense. Inmore details, a value acquired by integrating a function of a temporalchange in the relative decreased amount of the electrostatic force in aportion in which the user's finger is brought into contact with thecontact face 11 with respect to time is configured to be less than 10ms. For example, the control circuit 21 performs control of a timeinterval for changing the electrode 17 controlled for detecting contactto be less than 10 ms. In the example illustrated in FIG. 18 , a timeinterval for changing the electrode 17 controlled for detecting contactis 0.925 ms. A decrease in the electrostatic force occurs within ashorter period than the time resolution of the tactile sense, and, evenin a case where the electrostatic force is decreased, the perceivedelectrostatic force is averaged over the whole finger not to be zero,and accordingly, an interruption of the presentation of a tactile senseis not perceived by the user.

In FIG. 18 , while an example is illustrated in which an electrode 17adjacent to the electrode 17 controlled for detecting contact on thecontact face 11 is an electrode 17 controlled next for detectingcontact, the tactile presentation device may employ a form in which theposition of the electrode 17 controlled for detecting contact isdiscretely changed. By discretely changing the position of the electrode17 controlled for detecting contact, timings at which the electrostaticforce decreases in a plurality of areas included within the contactportion where the user's finger touches the contact face 11 arediscrete. For this reason, the period in which the presented tactilesense is interrupted is further shortened, and the effect of user's noperception of an interruption of the tactile sense is further improved.

Fourth Embodiment 4

A tactile presentation device according to Embodiment 4 detects acontact position on a contact face 11 by using a mutual capacitancesystem. The configuration of a tactile presentation device is similar tothat of the case of Embodiment 1 illustrated in FIGS. 1 and 2 except forthe insides of a tactile panel 1 and a tactile panel driving unit 2.Similar to the case of Embodiment 3 illustrated in FIG. 15 , a tactilepanel 1 includes: a substrate 12, a plurality of rectangular electrodes17 arranged on the substrate 12 in a matrix pattern; and a cover layer15. Similarly, the tactile panel driving unit 2, as illustrated in FIG.15 , includes: a touch panel driving circuit 22; an electrode drivingcircuit 27; a switching unit 28; and a control circuit 21.

FIG. 19 is a schematic circuit diagram that illustrates the internalconfigurations of the touch panel driving circuit 22 and the switchingunit 28 according to Embodiment 4. The plurality of electrodes 17included in the tactile panel is configured by a plurality of electrodepairs each formed by one pair of electrodes 17 adjacent to each other.Each electrode 17 is connected to the switching unit 28 through a wiring18. The switching unit 28 is configured to connect some electrodes 17 tothe touch panel driving circuit 22 and connect the other electrodes 17to the electrode driving circuit 27 and to be able to switch theconnection of each electrode 17 to one side to the other side. Theswitching unit 28 performs the switching in units of electrode pairs. Inother words, two electrodes 17 included in an electrode pair have theconnections to be simultaneously switched and are connected to a samecircuit out of the touch panel driving circuit 22 and the electrodedriving circuit 27. The touch panel driving circuit 22 includes aplurality of signal input units 221 and a plurality of current detectingunits 222. The touch panel driving circuit 22 and the switching unit 28are configured such that, when an electrode pair is connected to thetouch panel driving circuit 22, one electrode 17 is connected to thesignal input unit 221, and the other electrode 17 is connected to thecurrent detecting unit 222. The signal input unit 221 inputs an ACsignal to one electrode 17, and the current detecting unit 222 detects acurrent signal flowing through the other electrode 17. The internalcircuit of the touch panel driving circuit 22 illustrated in FIG. 19corresponds to a detection circuit.

Electrostatic capacitance is generated between two electrodes 17, whichare included in an electrode pair, adjacent to each other. In a casewhere the signal input unit 221 inputs an AC signal to one electrode 17,an AC current flows between the two electrodes 17, and the currentdetecting unit 222 detects the AC current. In a case where a user'sfinger is brought into contact with a portion on the contact face 11that faces the electrode pair, electrostatic capacitance is generatedbetween the electrode pair and the finger, and the electrostaticcapacitance between the two electrodes 17 changes. In a case where theelectrostatic capacitance between the two electrodes 17 changes, the ACcurrent detected by the current detecting unit 222 changes. Theoperation of the switching unit 28 is controlled by the control circuit21, and the electrode pair connected to the touch panel driving circuit22 is specified under the control of the control circuit 21. The controlcircuit 21 compares the AC current detected by the current detectingunit 222 with a predetermined threshold and detects that whether theelectrostatic capacitance between the electrode pair connected to thetouch panel driving circuit 22 has been changed. In a case where theelectrostatic capacitance changes, the control circuit 21 specifies theelectrode pair connected to the touch panel driving circuit 22, therebydetecting a position with which the user's finger is brought intocontact. The contact position is a position on the contact face 11 thatfaces the electrode pair connected to the touch panel driving circuit22. The control circuit 21 outputs data representing the contactposition to the arithmetic operation unit 31. In this way, the tactilepresentation device detects a contact position on the contact face 11 byusing a mutual capacitance system.

In addition, the tactile presentation device may employ a form in whichnot only a contact position on the contact face 11 is detected but alsoa position at which an object approaches is detected in a case where theconductive object such as a finger approaches the contact face 11 withina predetermined distance. In such a form, in a case where an objectapproaches the contact face 11 within a predetermined distance,electrostatic capacitance is generated between the electrode pair andthe object, and, similarly, a position approached by the object on thecontact face 11 is detected.

The configuration of the electrode driving circuit 27 is similar to thatof Embodiment 3 illustrated in FIG. 16 . The control circuit 21 performscontrol of the switching unit 28 to connect each electrode pair toeither the touch panel driving circuit 22 or the electrode drivingcircuit 27. The control circuit 21 causes the switching unit 28 toconnect some electrode pairs to the touch panel driving circuit 22 andconnects the other electrode pairs to the electrode driving circuit 27.

In addition, the control circuit 21 causes the switching unit 28 tosequentially change the electrode pair to be connected to the touchpanel driving circuit 22. When the electrode pair connected to the touchpanel driving circuit 22 is changed, the switching unit 28 connects theelectrode pair that has been connected to the touch panel drivingcircuit 22 until now to the electrode driving circuit 27 and connectssome electrode pairs among a plurality of electrode pairs that have beenconnected to the electrode driving circuit 27 until now to the touchpanel driving circuit 22. In addition, the control circuit 21, bycontrolling the single-pole double-throw switches 271 of the electrodedriving circuit 27, connects an electrode 17 among the electrodes 17connected to the electrode driving circuit 27 that corresponds to anarea to which a tactile sense is to be presented to the AC voltagesource 272 and connects the other electrodes 17 to the ground.

Under the control of the control circuit 21, each of the plurality ofelectrode pairs is sequentially connected to the touch panel drivingcircuit 22, and detection of contact at a position on the contact face11 that faces each electrode pair is sequentially performed. Bysequentially connecting each electrode pair to the touch panel drivingcircuit 22, each electrode pair is sequentially controlled for detectingcontact on the contact face 11. In other words, the contact face 11 isscanned for detection of a contact position. After the completion of thescanning of the whole contact face 11, the control circuit 21 repeatsthe process of sequentially connecting each electrode pair to the touchpanel driving circuit 22. In this way, the scanning is repeated, and, ina case where a user contacts an arbitrary position on the contact face11, the contact point is detected. In a period other than the period inwhich an electrode 17 is connected to the touch panel driving circuit22, the electrode 17 is connected to the electrode driving circuit 27under the control of the control circuit 21. Some electrodes 17 areconnected to the AC voltage source 272, and the other electrodes 17 areconnected to the ground. As a result, a tactile sense is presented tothe contact face 11. In this way, the electrodes 17 are controlled forpresenting a tactile sense to the contact face 11.

FIG. 20 is a schematic view that illustrates an example of the tactilepanel 1 according to Embodiment 4. FIG. 20 illustrates an example inwhich the electrodes 17 are arranged in 4 rows x 6 columns. In FIG. 20 ,while a reference numeral 17 is assigned to one electrode, all therectangular electrodes illustrated in FIG. 20 are electrodes 17. Numbersof 0 to 5 are assigned to the electrodes 17 disposed along the Xdirection, numbers of 0 to 3 are assigned to the electrodes 17 disposedalong the Y direction, and the position of each electrode 17 isrepresented using a combination of an X-direction number and aY-direction number. In the example illustrated in FIG. 20 , an electrode17 arranged in an even-numbered column and an electrode 17 arranged inthe next column configure an electrode pair. For example, electrodes 17located at positions (0, 0) and (1, 0) configure an electrode pair.Areas corresponding to the electrodes 17 located at positions of (1, 1),(1, 2), (2, 1), and (2, 2) are assumed to be target areas 16 to which atactile sense is presented.

FIG. 21 is a timing diagram that illustrates an example of the operationof each electrode 17 according to Embodiment 4. In FIG. 21 , the leftside to the right side represent the elapse of time, and t₀ to t₁₂represent respective time points. FIG. 21 illustrates the states ofelectrodes 17 of which positions are represented as (X, Y) at each timepoint. FIGS. 22A to 22C are schematic views that illustrate the statesof the tactile panel 1 at specific timings according to Embodiment 4.FIGS. 22A, 22B, and 22C respectively illustrate the states of periods oft₁ to t₂, t₂ to t₃, and t₃ to t₄. A state in which the electrode 17 isconnected to the ground is denoted by T_(G), a state in which theelectrode 17 is connected to the AC voltage source 272 is denoted byT_(D), a state in which the electrode 17 is connected to the signalinput unit 221 is denoted by S_(T), and a state in which the electrode17 is connected to the current detecting unit 222 is denoted by S_(R).

As illustrated in FIGS. 21 and 22A to 22C, in a period of t₁ to t₂,electrode pairs located at positions of (2, 0) and (3, 0) and electrodepairs located at positions of (4, 2) and (5, 2) are controlled fordetecting contact. In a period of t₂ to t₃, electrode pairs located atpositions of (4, 0) and (5, 0) and electrode pairs located at positionsof (0, 3) and (1, 3) are controlled for detecting contact. In a periodof t₃ to t₄, electrode pairs located at positions of (0, 1) and (1, 1)and electrode pairs located at positions of (2, 3) and (3, 3) arecontrolled for detecting contact. In this way, each electrode pair issequentially controlled for detecting contact, and detection of contactat each position on the contact face 11 is sequentially performed. Inaddition, in periods other than the periods in which the electrode pairsare controlled for detecting contact, electrode 17 located at positionsof (1, 1), (1, 2), (2, 1), and (2, 2) are connected to the AC voltagesource 272, and the other electrodes 17 are connected to the ground. Asa result, a tactile sense is presented to a target area 16 within thecontact face 11.

As above, also in this embodiment, in a period in which some electrodes17 are controlled for detecting contact on the contact face 11, theother electrodes 17 are controlled for presenting a tactile sense to thecontact face 11. For this reason, the tactile presentation device cansimultaneously perform the presentation of a tactile sense and thedetection of a contact position. In addition, the electrode 17controlled for detecting contact on the contact face 11 is sequentiallychanged, and each electrode 17 is controlled for presenting a tactilesense to the contact face 11 at timings other than the timing at whichthe electrode 17 is controlled for detecting contact. While thepresentation of a tactile sense is not performed at a position at whichthe detection of contact on the contact face 11 is performed, theposition at which the contact is detected is sequentially moved, andaccordingly, the presentation of a tactile sense is not interrupted onthe whole contact face 11. Similar to Embodiment 3, a decrease in theelectrostatic force occurs within a shorter period than the timeresolution of a tactile sense, and a perceived electrostatic force isaveraged over the whole finger to be non-zero even in a case where theelectrostatic force is decreased, and accordingly, an interruption ofthe presentation of a tactile sense is not perceived by a user.Accordingly, also in this embodiment, the tactile presentation devicecan simultaneously perform the presentation of a tactile sense and thedetection of a contact position, and a tactile sense felt by a userduring the use of the tactile presentation device is not interrupted.

In Embodiments 3 and 4 described above, while a form in which thecontrol circuit 21 is included in addition to the touch panel drivingcircuit 22, the electrode driving circuit 27, and the switching unit 28is illustrated, the tactile presentation device may employ a form notincluding the control circuit 21. For example, the tactile presentationdevice may employ a form in which the touch panel driving circuit 22 hasfunctions equivalent to those of the control circuit 21 or a form inwhich the functions equivalent to those of the control circuit 21 areincluded in the touch panel driving circuit 22, the electrode drivingcircuit 27, and the switching unit 28 in a distributed manner.Furthermore, the tactile presentation device may employ a form in whichthe operations of the touch panel driving circuit 22, the electrodedriving circuit 27, and the switching unit 28 are directly controlled bythe arithmetic operation unit 31.

In Embodiments 3 and 4, while a form in which a tactile sense ispresented by applying an AC voltage to a specific electrode 17 isillustrated, the tactile presentation device may employ a form in whicha tactile sense is presented using a method other than methods that aregenerally known. For example, the tactile presentation device may employa form in which a tactile sense is presented by applying the same ACvoltage to all the electrodes 17. In addition, the tactile presentationdevice may employ a form in which a tactile sense is presented byapplying voltages having opposite polarities to the electrodes 17adjacent to each other.

Furthermore, the tactile presentation device may employ a form in whicha position at which an object approaches or is in contact with thecontact face 11 is detected using a generally-known method other thanthe methods described in Embodiments 3 and 4. For example, the tactilepresentation device may employ a form in which a current value of avoltage signal applied to the electrodes 17 for presenting a tactilesense is measured, and contact or approach of an object is detectedaccording to a change in the measured current value. In Embodiments 3and 4, while a form in which the electrodes 17 are arranged in a matrixpattern has been illustrated, the tactile presentation device may employa form in which the electrodes 17 are arranged in any other form. Forexample, the tactile presentation device may employ a form in which theelectrodes 17 are arranged in a shape to be represented through atactile sense.

Embodiment 5

FIG. 23 is a block diagram that illustrates the internal configurationof a tactile panel 1 according to Embodiment 5. The configuration of atactile presentation device according to Embodiment is similar to thatof Embodiment 1 or 2 except for the tactile panel 1. An X electrode 13is configured by a plurality of sub X electrodes 132, and a Y electrode14 is configured by a plurality of sub Y electrodes 142. The pluralityof sub X electrodes 132 configuring the X electrode 13 are arranged inparallel to be adjacent to each other and are commonly connected.Similarly, the plurality of sub Y electrodes 142 configuring the Yelectrode 14 are arranged in parallel to be adjacent to each other andare connected to each other. In the drawing, while an example in whichthe X electrode 13 is configured by three sub X electrodes 132 isillustrated, the X electrode 13 may be configured by two sub Xelectrodes 132 or four or more sub X electrodes 132. Similarly, the Yelectrode 14 may be configured by two sub Y electrodes 142 or four ormore sub Y electrodes 142. The other configurations of the tactile panel1 are similar to those of Embodiment 1 or 2.

The operation of the tactile presentation device according to thisembodiment is similar to that according to Embodiment 1 or 2. In otherwords, some of the X electrodes 13 and the Y electrodes 14 arecontrolled for detecting a position at which an object is in contactwith or approaches a contact face 11, and the X electrode 13 and the Yelectrode 14 controlled for detecting a contact position or anapproaching position of the object are sequentially changed. At timingsother than a timing at which each of X electrodes 13 and Y electrodes 14is controlled for detecting contact, each of X electrodes 13 and Yelectrodes 14 is controlled for presenting a tactile sense to thecontact face 11. In this way, a plurality of sub X electrodes 132, whichconfigure one X electrode 13, adjacent to each other and a plurality ofsub Y electrodes 142, which configure one Y electrode 14, adjacent toeach other are used for detecting a position, and the other sub Xelectrodes 132 and the other sub Y electrode 142 are used for presentinga tactile sense. Similar to Embodiments 1 and 2, also in thisembodiment, the tactile presentation device can simultaneously performthe presentation of a tactile sense and the detection of a contactposition, and a tactile sense felt by a user during the use of thetactile presentation device is not interrupted.

It is preferable that a distance between the centers of a plurality ofsub X electrodes 132 configuring X electrodes 13 in the Y directionbetween the X electrodes 13 adjacent to each other is less than 10 mmsuch that the sub X electrode 132 used for detecting a position and thesub X electrode 132 used for presenting a tactile sense are includedinside a contact portion where a user's finger touches the contact face11. It is more preferable that this distance is less than 6 mm.Similarly, a distance between the centers of a plurality of sub Yelectrodes 142 configuring Y electrodes 14 in the X direction betweenthe Y electrodes 14 adjacent to each other is preferably less than 10 mmand is more preferably less than 6 mm.

Embodiment 6

Embodiment 6 is a modification of Embodiment 2. In Embodiment 2, in acase where a voltage is applied from the AC voltage source 224 to the Xelectrode 13 or the Y electrode 14 in a state in which a user's fingeris not brought into contact with the contact face 11, parasitic currentsflow through the parasitic capacitance of each X electrode 13 and theparasitic capacitance of each Y electrode 14, and the current detectingunit 223 detects these parasitic currents. The parasitic capacitance ofan X electrode 13 is formed between the X electrode 13 and a pluralityof Y electrodes 14 intersecting with the X electrode 13 and between theX electrode 13 and an X electrode 13 adjacent to the X electrode 13. Theparasitic capacitance of a Y electrode 14 is formed between the Yelectrode 14 and a plurality of X electrodes 13 intersecting with the Yelectrode 14 and between the Y electrode 14 and a Y electrode 14adjacent to the Y electrode 14. Depending on the design of the tactilepanel 1, the value of such parasitic capacitance becomes large, andthere is concern that a parasitic currents flowing through the parasiticcapacitance causes a problem. Since the parasitic current may occupymost of the dynamic range of a current value that can be detected by thecurrent detecting unit, it is preferable to decrease the parasiticcurrent. Embodiment 6 is a form for decreasing the parasitic current.

FIG. 24 is a block diagram that illustrates the internal configurationsof a tactile panel 1 and a tactile panel driving unit 2 according toEmbodiment 6. An X electrode driving circuit 23 is connected to a touchpanel driving circuit 22. In addition, a Y electrode driving circuit 24is connected to the touch panel driving circuit 22. As will be describedlater, the internal configurations of the touch panel driving circuit22, the X electrode driving circuit 23, and the Y electrode drivingcircuit 24 are different from those according to Embodiment 1 and 2. Thetouch panel driving circuit 22 can supply a voltage generated by aninternal AC voltage source to the X electrode driving circuit 23 and theY electrode driving circuit 24. The other parts of the tactilepresentation device are similar to those according to Embodiment 1.

FIG. 25 is a schematic circuit diagram that illustrates the internalconfiguration of the touch panel driving circuit 22 according toEmbodiment 6. The touch panel driving circuit 22 includes an AC voltagesource 225. The AC voltage source 225 is connected to a plurality ofcurrent detecting units 223. In addition, the AC voltage source 225 isconnected to the X electrode driving circuit 23 and the Y electrodedriving circuit 24. A high pass filter (HPF) 226 is disposed between thecurrent detecting unit 223 and a first switching unit 25. In addition, ahigh pass filter 226 is disposed between the current detecting unit 223and a second switching unit 26. The AC voltage source 225 generates anAC voltage having a higher frequency than that of a first AC voltagesource 232 included in the X electrode driving circuit 23 and a secondAC voltage source 242 included in the Y electrode driving circuit 24.The high pass filter 226 has characteristics for transmitting a currenthaving the same frequency (for example, 100 kHz) as that of an ACvoltage generated by the AC voltage source 225 and blocking a currenthaving the same frequency (for example, 1000 Hz and 1240 Hz) as that ofan AC voltage generated by the first AC voltage source 232 and thesecond AC voltage source 242. The other parts of the touch panel drivingcircuit 22 are similar to those according to Embodiment 1.

FIG. 26 is a schematic circuit diagram that illustrates the internalconfiguration of the X electrode driving circuit 23 according toEmbodiment 6. As described above, the AC voltage source 225 included inthe touch panel driving circuit 22 is connected to the X electrodedriving circuit 23. The X electrode driving circuit 23 includes avoltage superimposing unit 233 that superimposes a voltage generated bythe AC voltage source 225 on a voltage generated by the first AC voltagesource 232. In addition, the X electrode driving circuit 23 includes avoltage superimposing unit 234 that superimposes the voltage generatedby the AC voltage source 225 on the ground voltage. Each single-poledouble-throw switch 231 performs switching of a connection between eachX electrode 13 and an output node N1 of the voltage superimposing unit233 or an output node N2 of the voltage superimposing unit 234. Theother parts of the X electrode driving circuit 23 are similar to thoseaccording to Embodiment 1.

The operations of the voltage superimposing unit 233 and the voltagesuperimposing unit 234 will be described. FIGS. 27A to 27D are graphsthat schematically illustrate the waveforms of voltages acquired by theX electrode driving circuit 23 according to Embodiment 6. In thedrawing, the horizontal axis represents the time, and the vertical axisrepresents the voltage. The amplitude of the AC voltage generated by thefirst AC voltage source 232 is assumed to be 100 V, and a firstfrequency f1 is assumed to be 1000 Hz. The amplitude of the AC voltagegenerated by the AC voltage source 225 of the touch panel drivingcircuit 22 is assumed to be 1 V, and the frequency is assumed to be 100kHz. FIG. 27A schematically illustrates the waveform of the AC voltagegenerated by the first AC voltage source 232, and FIG. 27B schematicallyillustrates the waveform of the AC voltage generated by the AC voltagesource 225. FIG. 27C schematically illustrates the waveform of a voltageoutput by the output node N1 of the voltage superimposing unit 233. Thevoltage output from the output node N1 is a voltage acquired by addingthe AC voltage generated by the first AC voltage source 232 and the ACvoltage generated by the AC voltage source 225. FIG. 27D schematicallyillustrates the waveform of a voltage output by the output node N2 ofthe voltage superimposing unit 234. The voltage output from the outputnode N2 is a voltage acquired by adding the voltage of the ground, forexample, a voltage of 0 V and the AC voltage generated by the AC voltagesource 225. In this way, the voltage superimposing unit 233 and thevoltage superimposing unit 234 have a function of adding given twovoltages and outputting a resultant voltage.

FIG. 28 is a schematic circuit diagram that illustrates the internalconfiguration of the Y electrode driving circuit 24 according toEmbodiment 6. As described above, the AC voltage source 225 included inthe touch panel driving circuit 22 is connected to the Y electrodedriving circuit 24. The Y electrode driving circuit 24 includes avoltage superimposing unit 243 that superimposes the voltage generatedby the AC voltage source 225 on the voltage generated by the second ACvoltage source 242. In addition, the Y electrode driving circuit 24includes a voltage superimposing unit 244 that superimposes the voltagegenerated by the AC voltage source 225 on the ground voltage. Eachsingle-pole double-throw switch 241 performs switching of a connectionbetween each Y electrode 14 and an output node N3 of the voltagesuperimposing unit 243 or an output node N4 of the voltage superimposingunit 244. The other parts of the Y electrode driving circuit 24 aresimilar to those according to Embodiment 1.

The operations of the voltage superimposing unit 243 and the voltagesuperimposing unit 244 will be described. FIGS. 29A to 29D are graphsthat schematically illustrate the waveforms of voltages acquired by theY electrode driving circuit 24 according to Embodiment 6. In thedrawing, the horizontal axis represents the time, and the vertical axisrepresents the voltage. The amplitude of the AC voltage generated by thesecond AC voltage source 242 is assumed to be 100 V, and a secondfrequency f2 is assumed to be 1240 Hz. The amplitude of the AC voltagegenerated by the AC voltage source 225 of the touch panel drivingcircuit 22 is assumed to be 1 V, and the frequency is assumed to be 100kHz. FIG. 29A schematically illustrates the waveform of the AC voltagegenerated by the second AC voltage source 242, and FIG. 29Bschematically illustrates the waveform of the AC voltage generated bythe AC voltage source 225. FIG. 29C schematically illustrates thewaveform of a voltage output by the output node N3 of the voltagesuperimposing unit 243. The voltage output from the output node N3 is avoltage acquired by adding the AC voltage generated by the second ACvoltage source 242 and the AC voltage generated by the AC voltage source225. FIG. 29D schematically illustrates the waveform of a voltage outputby the output node N4 of the voltage superimposing unit 244. The voltageoutput from the output node N4 is a voltage acquired by adding thevoltage of the ground, for example, a voltage of 0 V and the AC voltagegenerated by the AC voltage source 225. In this way, the voltagesuperimposing unit 243 and the voltage superimposing unit 244 have afunction of adding given two voltages and outputting a resultantvoltage.

In Embodiment 2, the X electrode 13 is connected to one of the first ACvoltage source 232, the ground, and the touch panel driving circuit 22.In contrast to this, in Embodiment 6, the X electrode 13 is connected toone of the output node N1 of the voltage superimposing unit 233, theoutput node N2 of the voltage superimposing unit 234, and the touchpanel driving circuit 22. In a state in which the X electrode 13 isconnected to the touch panel driving circuit 22, as illustrated in FIG.27B, the AC voltage generated by the AC voltage source 225 is applied tothe X electrode 13. In a state in which the X electrode 13 is connectedto the output node N1, as illustrated in FIG. 27C, a voltage acquired byadding the AC voltage generated by the first AC voltage source 232 andthe AC voltage generated by the AC voltage source 225 is applied to theX electrode 13. In a state in which the X electrode 13 is connected tothe output node N2, as illustrated in FIG. 27D, a voltage acquired byadding the voltage of the ground voltage and the AC voltage generated bythe AC voltage source 225 is applied to the X electrode 13.

In Embodiment 2, the Y electrode 14 is connected to one of the second ACvoltage source 242, the ground, and the touch panel driving circuit 22.In contrast to this, in Embodiment 6, the Y electrode 14 is connected toone of the output node N3 of the voltage superimposing unit 243, theoutput node N4 of the voltage superimposing unit 244, and the touchpanel driving circuit 22. In a state in which the Y electrode 14 isconnected to the touch panel driving circuit 22, as illustrated in FIG.29B, the AC voltage generated by the AC voltage source 225 is applied tothe Y electrode 14. In a state in which the Y electrode 14 is connectedto the output node N3, as illustrated in FIG. 29C, a voltage acquired byadding the AC voltage generated by the second AC voltage source 242 andthe AC voltage generated by the AC voltage source 225 is applied to theY electrode 14. In a state in which the Y electrode 14 is connected tothe output node N4, as illustrated in FIG. 29D, a voltage acquired byadding the voltage of the ground voltage and the AC voltage generated bythe AC voltage source 225 is applied to the Y electrode 14.

The voltage superimposing units 233, 234, 243, and 244 are configuredsuch that the amplitudes of components of the frequency (in thisembodiment 100 kHz) of the voltages generated by the AC voltage source225 of the touch panel driving circuit 22 are the same in the voltagesapplied to the X electrode 13 and the Y electrode 14. In other words,voltages including a component having the same frequency and the sameamplitude as those of the voltage applied to the X electrode 13 and theY electrode 14 connected to the touch panel driving circuit 22 areapplied to the X electrode 13 connected to the output node N1, the Xelectrode 13 connected to the output node N2, the Y electrode 14connected to the output node N3, and the Y electrode 14 connected to theoutput node N4. When the frequency component of the voltage generated bythe AC voltage source 225 of the touch panel driving circuit 22 isfocused in the voltages applied to the X electrode 13 and the Yelectrode 14, all the X electrodes 13 and the Y electrodes 14 are drivenwith the same amplitude and the same phase. For this reason, in a casewhere a voltage is applied from the AC voltage source 225 to the Xelectrode 13 or the Y electrode 14 in a state in which a user's fingeris not brought into contact with the contact face 11, a voltage betweenthe electrodes configuring parasitic capacitance is constant, and nocurrent flows through the parasitic capacitance.

Here, the tactile panel 1, as illustrated in FIG. 24 , is assumed toinclude five X electrodes X₀ to X₄ and six Y electrodes Y₀ to Y₅, and astate in which the X electrode X₁ is connected to the touch paneldriving circuit 22 will be considered. At this time, in the X electrodeX₁, intersections of the X electrode X₁ and the Y electrodes Y₀ to Y₅,an adjacent portion between the X electrode X₁ and the X electrode X₀,and an adjacent portion between the X electrode X₁ and the X electrodeX₂, parasitic capacitance is formed. In addition, the X electrode X₁ isconnected to the AC voltage source 225 through the current detectingunit 223, and the voltage generated by the AC voltage source 225 issuperimposed in all the other electrodes.

FIG. 30 is a circuit diagram acquired by modeling a state in which the Xelectrode X₁ is connected to the AC voltage source 225 through thecurrent detecting unit 223, and a voltage generated by the AC voltagesource 225 is superimposed in all the other electrodes. The X electrodeX₁ corresponds to an electrode P1 in the drawing, and all the otherelectrodes correspond to an electrode P2 in the drawing. Parasiticcapacitance Cp is present between the electrodes P1 and P2. However,since an electric potential difference between the electrode P1 and theelectrode P2 configuring the parasitic capacitance Cp does not change, acurrent of the component of the frequency of the voltage generated bythe AC voltage source 225 does not flow through the parasiticcapacitance Cp. For this reason, the current detecting unit 223 does notdetect any current.

FIG. 31 is a circuit diagram that models the states of the electrodesaccording to Embodiment 2. In Embodiment 2, the X electrode X₁ isconnected to the AC voltage source 224 having a frequency of 100 kHzthrough the current detecting unit 223, and most of the other electrodesare connected to the ground, the first AC voltage source 232 having afrequency of 1000 Hz, or the second AC voltage source 242 having afrequency of 1240 Hz. When the component of 100 kHz that is thefrequency of the voltage generated by the AC voltage source 224 isfocused, the state can be represented as a model in which most of theelectrodes other than the X electrode X₁ are connected to the ground.The electrode P1 illustrated in FIG. 31 corresponds to the X electrodeX₁, and the electrode P2 corresponds to an electrode of combining mostof the other electrodes. Since an electric potential difference betweenthe electrode P1 and the electrode P2 configuring the parasiticcapacitance Cp changes, a current flows through the parasiticcapacitance Cp. This current is a parasitic current that flows in astate in which a user's finger is not brought into contact with thecontact face 11 in Embodiment 2.

The parasitic capacitance was measured in the tactile panel 1 accordingto Embodiment 6 that was actually produced, and the parasiticcapacitance of one X electrode 13 was 240 pF, and the parasiticcapacitance of one Y electrode 14 was 170 pF. In addition, in a casewhere a user's finger was brought into contact with the contact face 11,electrostatic capacitance between the electrode and the finger was 5 pF.In Embodiment 2, 240/245 of the dynamic range of the current value thatcan be detected by the current detecting unit 223 is occupied by aparasitic current that is basically unnecessary. In contrast to this, inEmbodiment 6, the parasitic current is decreased to be almost zero, andthe SN ratio of the current detected by the current detecting unit 223is improved.

FIG. 32 is a circuit diagram that illustrates an example of theconfiguration of the voltage superimposing units 233 and 234 accordingto Embodiment 6. The voltage superimposing unit 233 is configured by acapacitor C1. One end of the capacitor C1 is connected to the outputnode N1, and the other end is connected to the AC voltage source 225 ofthe touch panel driving circuit 22. The first AC voltage source 232 isconnected to the one end of the capacitor C1 and the output node N1.Resistance R1 denoted inside the first AC voltage source 232 representsthe output impedance of the first AC voltage source 232. The voltagesuperimposing unit 234 includes a resistor R3 connected between theoutput node N2 and the ground, and a resister R2 connected between theoutput node N2 and the AC voltage source 225. The ratio between theresistor R2 and the resistor R3 is set such that, in voltages outputfrom the output node N1 and the output node N2, the amplitudes ofcomponents of the frequency of the voltage generated by the AC voltagesource 225 are the same. The voltage superimposing units 243 and 244 aresimilarly configured.

The configuration of the tactile presentation device for decreasing aparasitic current described in Embodiment 6 described above may beapplied to Embodiment 3 in which a plurality of electrodes arranged in amatrix pattern are included. Also in the form in which the configurationfor decreasing a parasitic current is applied to Embodiment 3, effectssimilar to those according to Embodiment 6 can be acquired. In addition,the configuration for decreasing a parasitic current described inEmbodiment 6 may be applied to a tactile presentation device notincluding the third control unit. In other words, also in a tactilepresentation device in which electrodes used for presenting a tactilesense and electrodes used for detecting contact or approach of an objectare separately arranged along the contact face, the configuration fordecreasing a parasitic current can be applied, and effects similar tothose according to Embodiment 6 can be acquired.

In Embodiments 1 to 6 described above, while a form in which the contactface 11 is a flat face has been illustrated, the tactile presentationdevice may employ a form in which the contact face 11 is a curved face.In addition, in Embodiments 1 to 6, while a form in which the tactilepresentation device is a computer such as a smartphone has beenillustrated, the tactile presentation device may employ various formssuch as a form being built in an automated teller machine (ATM) and thelike. Furthermore, in Embodiments 1 to 6, while a form in which thetactile presentation device includes the display panel 36 has beenillustrated, the tactile presentation device may employ a form notincluding the display panel 36.

According to the present disclosure, a tactile presentation device hassuperior effects such as being capable of simultaneously performing thepresentation of a tactile sense and the detection of a contact positionand not causing interrupt of a tactile sense felt by a user during theuse of the tactile presentation device.

It is to be noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise.

It is to be noted that the disclosed embodiment is illustrative and notrestrictive in all aspects. The scope of the present invention isdefined by the appended claims rather than by the description precedingthem, and all changes that fall within metes and bounds of the claims,or equivalence of such metes and bounds thereof are therefore intendedto be embraced by the claims.

What is claimed is:
 1. A tactile presentation device comprising: acontact face; and a plurality of electrodes arranged in parallel,wherein at least one of the plurality of the electrodes is used fordetecting a contact or approach of an object toward the contact face andfor presenting a tactile sense to the contact face, and a voltage signalfor detecting a contact or approach of an object toward the contact faceis applied one after another to the electrodes not adjacent to eachother according to elapse of time.
 2. A tactile presentation devicecomprising: a contact face; and a plurality of electrodes arranged inparallel, wherein at least one of the plurality of the electrodes isused for detecting a contact or approach of an object toward the contactface and for presenting a tactile sense to the contact face, and aposition of the electrode applied a voltage signal for detecting acontact or approach of an object toward the contact face is changeddiscretely according to elapse of time in order to scan the contactface.
 3. The tactile presentation device according to claim 1, whereinthe plurality of the electrodes include: a plurality of X electrodesarranged in parallel, and a plurality of Y electrodes arranged inparallel to intersect the X electrodes.
 4. The tactile presentationdevice according to claim 2, wherein the plurality of the electrodesinclude: a plurality of X electrodes arranged in parallel, and aplurality of Y electrodes arranged in parallel to intersect the Xelectrodes.